Vapor chamber, electronic device, metallic sheet for vapor chamber and manufacturing method of vapor chamber

ABSTRACT

A liquid flow path portion of a vapor chamber according to this invention includes a first main flow groove, a second main flow groove and a third main flow groove. A first convex array including a plurality of first convex portions arranged via a first communicating groove is provided between the first main flow groove and the second main flow groove. A second convex array including a plurality of second convex portions arranged via a second communicating groove is provided between the second main flow groove and the third main flow groove. The main flow groove includes a first intersection at which at least a part of the first communicating groove faces each second convex portion and a second intersection at which at least a part of the second communicating groove faces each first convex portion.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.16/488,843, filed Aug. 26, 2019, which is the national phase ofPCT/JP2018/006758, which claims priority to Japanese Patent Application2017-217633, Japanese Patent Application 2017-217593, and JapanesePatent Application 2017-033622, the contents of each of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a vapor chamber including a sealedspace in which a working fluid is enclosed, an electronic device, ametallic sheet for the vapor chamber and a manufacturing method of thevapor chamber.

BACKGROUND ART

A device accompanied with heat generation such as a central processingunit (CPU), a light-emitting diode (LED) and a power semiconductor,which is used in a mobile terminal and the like including a portableterminal or a tablet terminal, is cooled by a heat release member suchas a heat pipe (for example, see Patent Literatures 1 to 5.) In recentyears, to make a mobile terminal etc. thinner, thickness reduction ofthe heat release member has been requested, and development has beenadvanced for a vapor chamber which can be thinner than the heat pipe. Inthe vapor chamber, a working fluid is enclosed, and the working fluidabsorbs heat in the device and releases the heat to the outside, wherebythe device is cooled.

More specifically, the working fluid in the vapor chamber evaporates toturn into a vapor by receiving heat from the device at a portion closeto the device (an evaporating portion.) After that, the vapor moves to aposition away from the evaporating portion, and is cooled and liquidizedby condensation. In the vapor chamber, a liquid flow path portion as acapillary structure (wick) is provided, and the working fluid in liquidform is transported toward the evaporating portion by passing throughthe liquid flow path portion, and at the evaporating portion, receivesthe heat again to evaporate. In this way, the working fluid transfersthe heat of the device by circulating in the vapor chamber whileexecuting a change of phase, that is, repeating evaporation andcondensation, which improves heat release efficiency.

Incidentally, the liquid flow path portion includes a plurality ofgrooves extending in a first direction. The working fluid obtains thrusttoward the evaporating portion by receiving capillary action, and passesthrough the grooves toward the evaporating portion. Also, to reciprocatethe working fluid in the grooves adjacent to each other, another grooveextending in a second direction orthogonal the first direction isprovided. In this way, in the liquid flow path portion, a plurality ofgrooves are formed to be lattice-shaped, whereby the working fluid isevenly distributed in the liquid flow path portion.

[Patent Literature 1]

Japanese Patent Laid-Open No. 2015-59693

[Patent Literature 2]

Japanese Patent Laid-Open No. 2015-88882

[Patent Literature 3]

Japanese Patent Laid-Open No. 2016-17702

[Patent Literature 4]

Japanese Patent Laid-Open No. 2016-50682

[Patent Literature 5]

Japanese Patent Laid-Open No. 2016-205693

DISCLOSURE OF THE INVENTION

However, when a plurality of grooves are formed in a lattice shape, aproblem can occur due to a pressure received from the outside air.

That is, the vapor chamber is constituted by two metallic sheets, andthe above-described grooves are formed on at least one metallic sheet.Thereby, in a portion where the grooves are formed in the metallicsheet, a thickness of a metal material becomes small. Since a space inthe liquid flow path portion is depressurized, the metallic sheetreceives a pressure in a direction of being recessed inwardly fromoutside air. Consequently, the metallic sheet has a risk of beingrecessed inwardly along the grooves. In particular, when thicknessreduction of the vapor chamber is requested as described above, thethickness of metallic sheets become smaller, and recess can be easilygenerated.

At an intersection at which the grooves orthogonal to each otherintersect, when the metallic sheet is recessed along the groovesextending in the second direction, the corresponding recess traversingthe grooves along the first direction can be formed. In such a case, across-sectional area of a flow path of the grooves along the firstdirection is reduced, which can increase flow path resistance of theworking fluid. This reduces a transport function of the working fluid inliquid form toward the evaporating portion, and the supply amount of theworking fluid to the evaporating portion can be reduced. In such a case,such a problem occurs that the amount of heat transport from theevaporating portion is reduced, and thermal transport efficiency islowered.

The present invention is made considering this point, and an object ofthe present invention is to provide a vapor chamber which secures thecross-sectional area of the flow path of the liquid flow path portion toimprove the transport function of the working fluid in liquid form andimproves the thermal transport efficiency, an electronic device, ametallic sheet for the vapor chamber and a manufacturing method of thevapor chamber.

This invention provides a vapor chamber in which a working fluid isenclosed, the vapor chamber including:

a first metallic sheet;

a second metallic sheet provided on the first metallic sheet; and

a sealed space which is provided between the first metallic sheet andthe second metallic sheet and which includes a vapor flow path portionthrough which a vapor of the working fluid passes and a liquid flow pathportion through which the working fluid in liquid form passes,

wherein the liquid flow path portion is provided in a surface of thefirst metallic sheet on a side of the second metallic sheet,

the liquid flow path portion includes a first main flow groove, a secondmain flow groove and a third main flow groove, each of which extends ina first direction and through which the working fluid in liquid formpasses,

the first main flow groove, the second main flow groove and the thirdmain flow groove are arranged in this order in a second directionorthogonal to the first direction,

a first convex array which includes a plurality of first convex portionsarranged in the first direction via a first communicating groove isprovided between the first main flow groove and the second main flowgroove,

a second convex array which includes a plurality of second convexportions arranged in the first direction via a second communicatinggroove is provided between the second main flow groove and the thirdmain flow groove,

the first communicating groove allows communication between the firstmain flow groove and the second main flow groove,

the second communicating groove allows communication between the secondmain flow groove and the third main flow groove, and

the second main flow groove includes a first intersection at which atleast a part of the first communicating groove faces each second convexportion and a second intersection at which at least a part of the secondcommunicating groove faces each first convex portion.

Additionally, in the vapor chamber described above, it is acceptablethat the first intersection and the second intersection of the secondmain flow groove are adjacent to each other.

Additionally, in the vapor chamber described above, it is acceptablethat the second main flow groove includes a plurality of the firstintersections and a plurality of the second intersections, and

the first intersections and the second intersections of the second mainflow groove are alternately arranged.

Additionally, in the vapor chamber described above, it is acceptablethat the liquid flow path portion further includes a fourth main flowgroove which extends in the first direction and through which theworking fluid in liquid form passes,

the fourth main flow groove is arranged on an opposite side from thesecond main flow groove to the third main flow groove,

a third convex array which includes a plurality of third convex portionsarranged in the first direction via a third communicating groove isprovided between the third main flow groove and the fourth main flowgroove,

the third communicating groove allows communication between the thirdmain flow groove and the fourth main flow groove, and

the third main flow groove includes a first intersection at which atleast a part of the second communicating groove faces each third convexportion and a second intersection at which at least a part of the thirdcommunicating groove faces each second convex portion.

Additionally, in the vapor chamber described above, it is acceptablethat the first intersection and the second intersection of the thirdmain flow groove are adjacent to each other.

Additionally, in the vapor chamber described above, it is acceptablethat the third main flow groove includes a plurality of the firstintersections and a plurality of the second intersections, and

the first intersections and the second intersections of the third mainflow groove are alternately arranged.

Additionally, in the vapor chamber described above, it is acceptablethat the second metallic sheet includes a planar abutting surface whichabuts a surface of the first metallic sheet on a side of the secondmetallic sheet and covers the second main flow groove.

Additionally, in the vapor chamber described above, it is acceptablethat a width of the second main flow groove is larger than a width ofthe first convex portions and a width of the second convex portions.

Additionally, in the vapor chamber described above, it is acceptablethat a width of the first communicating groove is larger than a width ofthe first main flow groove and the width of the second main flow groove,and

a width of the second communicating groove is larger than the width ofthe second main flow groove and a width of the third main flow groove.

Additionally, in the vapor chamber described above, it is acceptablethat a depth of the first communicating groove is deeper than a depth ofthe first main flow groove and a depth of the second main flow groove,and

a depth of the second communicating groove is deeper than the depth ofthe second main flow groove and a depth of the third main flow groove.

Additionally, in the vapor chamber described above, it is acceptablethat a depth of the first intersection and a depth of the secondintersection of the second main flow groove are deeper than a depth of aportion between the first convex portions and the second convex portionsadjacent to each other in the second main flow groove.

Additionally, in the vapor chamber described above, it is acceptablethat the depth of the first intersection and the depth of the secondintersection of the second main flow groove are deeper than the depth ofthe first communicating groove and the depth of the second communicatinggroove.

Additionally, in the vapor chamber described above, it is acceptablethat each first convex portion includes a pair of first convex endportions provided at both end portions in the first direction and afirst convex intermediate portion provided between the pair of firstconvex end portions, and

a width of the first convex intermediate portion is smaller than a widthof the first convex end portions.

Additionally, in the vapor chamber described above, it is acceptablethat a rounded curved portion is provided at a corner portion of eachfirst convex portion.

Additionally, in the vapor chamber described above, it is acceptablethat the second metallic sheet includes a plurality of main flow grooveconvex portions, each of which protrudes toward the first main flowgroove, the second main flow groove and the third main flow groove ofthe first metallic sheet from a surface of the second metallic sheet ona side of the first metallic sheet.

Additionally, in the vapor chamber described above, it is acceptablethat a cross section of each main flow groove convex portion is formedto be curved.

Additionally, in the vapor chamber described above, it is acceptablethat the second metallic sheet includes a plurality of communicatinggroove convex portions, each of which protrudes toward the firstcommunicating groove and the second communicating groove of the firstmetallic sheet from the surface of the second metallic sheet on a sideof the first metallic sheet.

Additionally, in the vapor chamber described above, it is acceptablethat a cross section of each communicating groove convex portion isformed to be curved.

Also, the present invention provides an electronic device including:

a housing;

a device housed in the housing; and

a vapor chamber as described above, the vapor chamber is thermallycontacted to the device.

Also, the present invention provides a metallic sheet for a vaporchamber used for the vapor chamber including a sealed space whichincludes a vapor flow path portion in which a working fluid is enclosedand through which a vapor of the working fluid passes and a liquid flowpath portion through which the working fluid in liquid form passes, themetallic sheet for a vapor chamber including:

a first surface; and

a second surface provided on an opposite side from the first surface,

wherein the liquid flow path portion is provided to the first surface,

the liquid flow path portion includes a first main flow groove, a secondmain flow groove and a third main flow groove, each of which extends ina first direction and through which the working fluid in liquid formpasses,

the first main flow groove, the second main flow groove and the thirdmain flow groove are arranged in this order in a second directionorthogonal to the first direction,

a first convex array which includes a plurality of first convex portionsarranged in the first direction via a first communicating groove isprovided between the first main flow groove and the second main flowgroove,

a second convex array which includes a plurality of second convexportions arranged in the first direction via a second communicatinggroove is provided between the second main flow groove and the thirdmain flow groove,

the first communicating groove allows communication between the firstmain flow groove and the second main flow groove,

the second communicating groove allows communication between the secondmain flow groove and the third main flow groove, and

the second main flow groove includes a first intersection at which atleast a part of the first communicating groove faces each second convexportion and a second intersection at which at least a part of the secondcommunicating groove faces each first convex portion.

Also, the present invention provides a manufacturing method of a vaporchamber including a sealed space which is provided between a firstmetallic sheet and a second metallic sheet and in which a working fluidis enclosed, the sealed space including a vapor flow path portionthrough which a vapor of the working fluid passes and a liquid flow pathportion through which the working fluid in liquid form passes, themanufacturing method for vapor chamber including:

half-etching in which a surface of the first metallic sheet on a side ofthe second metallic sheet is half-etched to form the liquid flow pathportion;

joining the first metallic sheet and the second metallic sheet such thatthe sealed space is formed between the first metallic sheet and thesecond metallic sheet; and

enclosing the working fluid in the sealed space,

wherein the liquid flow path portion includes a first main flow groove,a second main flow groove and a third main flow groove, each of whichextends in a first direction and through which the working fluid inliquid form passes,

the first main flow groove, the second main flow groove and the thirdmain flow groove are arranged in this order in a second directionorthogonal to the first direction,

a first convex array which includes a plurality of first convex portionsarranged in the first direction via a first communicating groove isprovided between the first main flow groove and the second main flowgroove,

a second convex array which includes a plurality of second convexportions arranged in the first direction via a second communicatinggroove is provided between the second main flow groove and the thirdmain flow groove,

the first communicating groove allows communication between the firstmain flow groove and the second main flow groove,

the second communicating groove allows communication between the secondmain flow groove and the third main flow groove, and

the second main flow groove includes a first intersection at which atleast a part of the first communicating groove faces each second convexportion and a second intersection at which at least a part of the secondcommunicating groove faces each first convex portion.

According to the present invention, the cross-sectional area of the flowpath of the liquid flow path portion is secured and the transportfunction of the working fluid in liquid form is improved, which improvesthe thermal transport efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic perspective view for explaining an electronicdevice according to a first embodiment of the present invention.

FIG. 2 is a top view showing a vapor chamber according to the firstembodiment of the present invention.

FIG. 3 is a cross-sectional view showing the vapor chamber of FIG. 2taken along the line A-A.

FIG. 4 is a top view of a lower metallic sheet of FIG. 2.

FIG. 5 is a bottom view of an upper metallic sheet of FIG. 2.

FIG. 6 is an enlarged top view showing a liquid flow path portion ofFIG. 4.

FIG. 7 is a cross-sectional view of FIG. 6 taken along the line B-B withaddition of an upper flow path wall portion of the upper metallic sheet.

FIG. 8 is a drawing for explaining a preparation step of the lowermetallic sheet in a manufacturing method of the vapor chamber accordingto the first embodiment of the present invention.

FIG. 9 is a drawing for explaining a first half-etching step of thelower metallic sheet in the manufacturing method of the vapor chamberaccording to the first embodiment of the present invention.

FIG. 10 is a drawing for explaining a second half-etching step of thelower metallic sheet in the manufacturing method of the vapor chamberaccording to the first embodiment of the present invention.

FIG. 11 is a drawing for explaining a temporary joint step in themanufacturing method of the vapor chamber according to the firstembodiment of the present invention.

FIG. 12 is a drawing for explaining a permanent joint step in themanufacturing method of the vapor chamber according to the firstembodiment of the present invention.

FIG. 13 is a drawing for explaining a enclosing step of a working fluidin the manufacturing method of the vapor chamber according to the firstembodiment of the present invention.

FIG. 14 is a drawing showing a modification of FIG. 6.

FIG. 15 is a top view showing a modification of a liquid flow pathconvex portion shown in FIG. 6.

FIG. 16 is a top view showing another modification of the liquid flowpath convex portion shown in FIG. 6.

FIG. 17 is a drawing showing another modification of FIG. 6.

FIG. 18 is a drawing showing another modification of FIG. 3.

FIG. 19 is an enlarged top view showing a liquid flow path portion avapor chamber according to a second embodiment of the present invention.

FIG. 20 is a cross-sectional view of FIG. 19 taken along the line C-Cwith addition of an upper flow path wall portion of the upper metallicsheet.

FIG. 21 is a cross-sectional view of FIG. 19 taken along the line D-Dwith addition of the upper flow path wall portion of the upper metallicsheet.

FIG. 22 is a cross-sectional view of FIG. 19 taken along the line E-Ewith addition of the upper flow path wall portion of the upper metallicsheet.

FIG. 23 is an enlarged cross-sectional view showing a main flow grooveconvex portion in a vapor chamber according to a third embodiment of thepresent invention, corresponding to FIG. 20.

FIG. 24 is an enlarged cross-sectional view showing a communicatinggroove convex portion in the vapor chamber according to the thirdembodiment of the present invention, corresponding to FIG. 21.

FIG. 25 is an enlarged cross-sectional view showing a communicatinggroove convex portion in the vapor chamber according to the thirdembodiment of the present invention, corresponding to FIG. 22.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments according to the present invention will beexplained with reference to drawings. Additionally, for convenience ofillustration and easy understanding, in the drawings attached to thepresent specification, the scale and an aspect ratio etc. areappropriately changed and exaggerated from those of a real product.

First Embodiment

A vapor chamber, an electronic device, a metallic sheet for the vaporchamber and a manufacturing method of the vapor chamber according to afirst embodiment of the present invention will be explained using FIGS.1 to 18. A vapor chamber 1 according to this embodiment is an apparatusmounted on an electronic device E for cooling a device D as a heatingelement housed in the electronic device E. As an example of the deviceD, an electronic device accompanied with heat generation (a device to becooled) such as a central processing unit (CPU), a light-emitting diode(LED) and a power transistor, which is used in a mobile terminal and thelike such as a portable terminal or a tablet terminal, can be listed.

Here, firstly, an explanation will be made on the electronic device E onwhich the vapor chamber 1 is mounted according to this embodiment takinga tablet terminal as an example. As shown in FIG. 1, the electronicdevice E (tablet terminal) includes a housing H, the device D housed inthe housing H and the vapor chamber 1. In the electronic device E shownin FIG. 1, a touch panel display TD is provided in a front surface ofthe housing H. The vapor chamber 1 is housed in the housing H andarranged to thermally contact to the device D. Thereby, heat generatedat the device D when the electronic device E is used can be received bythe vapor chamber 1. The heat received by the vapor chamber 1 isreleased to the outside of the vapor chamber 1 via a working fluid 2which will be described later. In this way, the device D is effectivelycooled. If the electronic device E is the tablet terminal, the device Dcorresponds to the central processing unit etc.

Next, the vapor chamber 1 according to this embodiment will beexplained. The vapor chamber 1 includes a sealed space 3 in which theworking fluid 2 is enclosed, and the working fluid 2 in the sealed space3 repeats change of phase, so that the device D of the electronic deviceE described above is effectively cooled.

The vapor chamber 1 is formed as a schematically thin plate. While thevapor chamber 1 may have any planar shape, a rectangle as shown in FIG.2 may be applied. In this case, the vapor chamber 1 includes four linearouter edges 1 a, 1 b forming a planar outline. Among these, two outeredges 1 a are formed along a first direction X which will be describedlater, and remained two outer edges 1 b are formed along a seconddirection Y which will be described later. For example, a planar shapeof the vapor chamber 1 may be a rectangle having one side of 1 cm andthe other side of 3 cm, or may be a square having one side of 15 cm. Thevapor chamber 1 may have any planar dimension.

As shown in FIGS. 2 and 3, the vapor chamber 1 includes a lower metallicsheet 10 (first metallic sheet) having an upper surface 10 a (firstsurface) and a lower surface 10 b (second surface) provided on anopposite side from the upper surface 10 a, and an upper metallic sheet20 (second metallic sheet) provided on the lower metallic sheet 10. Thelower metallic sheet 10 and the upper metallic sheet 20 both correspondto a metallic sheet for a vapor chamber. The upper metallic sheet 20includes a lower surface 20 a (a surface on a side of the lower metallicsheet 10) layered on the upper surface 10 a of the lower metallic sheet10 (a surface on a side of the upper metallic sheet 20) and an uppersurface 20 b provided on an opposite side from the lower surface 20 a.The device D which is an object of cooling is attached to the lowersurface 10 b of the lower metallic sheet 10 (especially, a lower surfaceof an evaporating portion 11 which will be described later.)

The thickness of the vapor chamber 1 is, for example, 0.1 mm to 1.0 mm.While FIG. 3 shows a case where a thickness T1 of the lower metallicsheet 10 and a thickness T2 of the upper metallic sheet 20 are equal,not limited to this, the thickness T1 of the lower metallic sheet 10 andthe thickness T2 of the upper metallic sheet 20 may be different.

The sealed space 3 in which the working fluid 2 is enclosed is formedbetween the lower metallic sheet 10 and the upper metallic sheet 20. Inthis embodiment, the sealed space 3 includes a vapor flow path portionthrough which a vapor of the working fluid 2 mainly passes (a lowervapor flow path recess 12 and an upper vapor flow path recess 21 whichwill be described later) and a liquid flow path portion 30 through whichthe working fluid 2 in liquid form mainly passes. As examples of theworking fluid 2, pure water, ethanol, methanol and acetone etc. can belisted.

The lower metallic sheet 10 and the upper metallic sheet 20 are joinedby diffused junction which will be described later. In the embodimentshown in FIGS. 2 and 3, an example in which the lower metallic sheet 10and the upper metallic sheet 20 are formed to be rectangular in a planarview is shown. However, this is not restrictive. Here, the planar viewis a state seen in a direction which is orthogonal to a surface at whichthe vapor chamber 1 receives heat from the device D (the lower surface10 b of the lower metallic sheet 10) as well as a surface at which thereceived heat is released (the upper surface 20 b of the upper metallicsheet 20), and for example, this corresponds to a state that the vaporchamber 1 is seen from an upper side (see FIG. 2) or seen from a lowerside.

Additionally, when the vapor chamber 1 is installed in the mobileterminal, depending on an attitude of the mobile terminal, the verticalrelationship between the lower metallic sheet 10 and the upper metallicsheet 20 may be changed. However, in this embodiment, for convenience, ametallic sheet which receives heat from the device D is called as thelower metallic sheet 10, while a metallic sheet which releases thereceived heat is called as the upper metallic sheet 20, and anexplanation will be made in a state that the lower metallic sheet 10 isdisposed at the lower side and the upper metallic sheet 20 is disposedat the upper side.

As shown in FIG. 4, the lower metallic sheet 10 includes the evaporatingportion 11 in which the working fluid 2 evaporates to generate a vapor,and the lower vapor flow path recess 12 (a first vapor flow path recess)provided in the upper surface 10 a and formed to be rectangular in aplanar view. In these components, the lower vapor flow path recess 12constitutes a part of the sealed space 3 described above, and is mainlyconfigured such that the vapor generated in the evaporating portion 11passes.

The evaporating portion 11 is disposed in the lower vapor flow pathrecess 12. The vapor in the lower vapor flow path recess 12 is diffusedin a direction away from the evaporating portion 11, and most of thevapor is transported to a peripheral portion with a relatively lowtemperature. Additionally, the evaporating portion 11 is a portion atwhich the working fluid 2 in the sealed space 3 evaporates by receivingheat from the device D attached to the lower surface 10 b of the lowermetallic sheet 10. Consequently, the term of the evaporating portion 11is not a concept limited to a portion overlapped with the device D, andis used as a concept including a portion which is not overlapped withthe device D but allows the working fluid 2 to evaporate. Here, theevaporating portion 11 can be provided at any portion of the lowermetallic sheet 10. However, in FIGS. 2 and 4, an example in which theevaporating portion 11 is provided at a center portion of the lowermetallic sheet 10 is shown. In this case, an operation of the vaporchamber 1 can be stabilized regardless of the attitude of the mobileterminal in which the vapor chamber 1 is installed.

As shown in FIGS. 3 and 4, in this embodiment, a plurality of lower flowpath wall portions 13 (a first flow path wall portion) protruding upwardfrom a bottom surface 12 a (which will be described later) of the lowervapor flow path recess 12 (a direction orthogonal to the bottom surface12 a) are provided in the lower vapor flow path recess 12 of the lowermetallic sheet 10. In this embodiment, an example in which the lowerflow path wall portions 13 extend to be elongated along the firstdirection X of the vapor chamber 1 (a longitudinal direction, a rightand left direction in FIG. 4) is shown. Each lower flow path wallportion 13 includes an upper surface 13 a (a first abutting surface, aprotruding end surface) abutting a lower surface 22 a of thecorresponding upper flow path wall portion 22 which will be describedlater. The upper surface 13 a is a surface which is not etched by twoetching steps which will be described later, and formed on the sameplane as the upper surface 10 a of the lower metallic sheet 10. Also,each lower flow path wall portion 13 is separated from each other witheven intervals, and disposed to be parallel with each other. In thisway, such a configuration is made that the vapor of the working fluid 2flows along a periphery of each lower flow path wall portion 13 and thevapor is transported to a peripheral portion of the lower vapor flowpath recess 12, which inhibits blocking of vapor flow. Also, each lowerflow path wall portion 13 is disposed to be overlapped with thecorresponding upper flow path wall portion 22 (which will be describedlater) of the upper metallic sheet 20 in a planar view, which improvesmechanical strength of the vapor chamber 1. A width w0 of each lowerflow path wall portion 13 is 0.1 mm to 30 mm for example, preferably 0.1mm to 2.0 mm, and the interval d between the lower flow path wallportions 13 adjacent to each other is 0.1 mm to 30 mm, preferably 0.1 mmto 2.0 mm. Here, the width w0 means the dimension of each lower flowpath wall portion 13 in the second direction Y orthogonal to the firstdirection X of each lower flow path wall portion 13, and for example,corresponds to a vertical direction in FIG. 4. Also, a height h0 of eachlower flow path wall portion 13 (in other words, a depth of the lowervapor flow path recess 12) (see FIG. 3) is preferably smaller than athickness T1 of the lower metallic sheet 10 which will be describedlater by 10 μm or more. In this case, the difference between thethickness T1 and the height h0, that is, the thickness of the metalmaterial of the lower metallic sheet 10 at a portion where the lowervapor flow path recess 12 is formed can be 10 μm or more. Thereby, thestrength of the corresponding portion can be secured, which preventsdeformation to be recessed inwardly to a pressure received from theoutside air. Such height h0 may be 10 μm to 300 μm. For example, when athickness T0 of the vapor chamber 1 is 0.5 mm and the thickness T1 ofthe lower metallic sheet 10 and a thickness T2 of the upper metallicsheet 20 are equal, the height h0 can be 200 μm.

As shown in FIGS. 3 and 4, a lower peripheral wall 14 is provided at aperipheral portion of the lower metallic sheet 10. The lower peripheralwall 14 is formed to surround the sealed space 3, especially the lowervapor flow path recess 12 to define the sealed space 3. Also, loweralignment holes 15 which execute positioning between the lower metallicsheet 10 and the upper metallic sheet 20 are respectively provided atfour corners of the lower peripheral wall 14 in a planar view.

In this embodiment, the upper metallic sheet 20 has substantially thesame configuration as in the lower metallic sheet 10 excluding the pointthat the liquid flow path portion 30 which will be described later isnot provided. Hereinafter, the configuration of the upper metallic sheet20 will be explained in more detail.

As shown in FIGS. 3 and 5, the upper metallic sheet 20 includes an uppervapor flow path recess 21 (a second vapor flow path recess) provided inthe lower surface 20 a. The upper vapor flow path recess 21 constitutesa part of the sealed space 3, and is mainly configured to diffuse thevapor generated in the evaporating portion 11 for cooling. Moreconcretely, the vapor in the upper vapor flow path recess 21 is diffusedin a direction away from the evaporating portion 11, and most of thevapor is transported to the peripheral portion with a relatively lowtemperature. Also, as shown in FIG. 3, a housing member Ha constitutinga part of the housing H such as the mobile terminal (see FIG. 1) isdisposed on the upper surface 20 b of the upper metallic sheet 20.Thereby, the vapor in the upper vapor flow path recess 21 is cooled bythe outside via the upper metallic sheet 20 and the housing member Ha.

As shown in FIGS. 2, 3 and 5, in this embodiment, a plurality of upperflow path wall portions 22 (a second flow path wall portion) protrudingfrom the bottom surface 21 a of the upper vapor flow path recess 21 to alower side (a direction perpendicular to the bottom surface 21 a) areprovided in the upper vapor flow path recess 21 of the upper metallicsheet 20. In this embodiment, an example in which the upper flow pathwall portions 22 extend to be elongated along the first direction X (aright and left direction of FIG. 5) of the vapor chamber 1 is shown.Each upper flow path wall portion 22 includes the planar lower surface22 a (a second abutting surface, a protruding end surface) which abutsthe upper surface 10 a of the lower metallic sheet 10 (morespecifically, the upper surface 13 a of each lower flow path wallportion 13 described above) and covers the liquid flow path portion 30.Also, each upper flow path wall portion 22 is separated from each otherwith even intervals and disposed to be parallel with each other. In thisway, such a configuration is made that the vapor of the working fluid 2flows along a periphery of each upper flow path wall portion 22 and thevapor is transported to a peripheral portion of the upper vapor flowpath recess 21, which inhibits blocking of vapor flow. Also, each upperflow path wall portion 22 is disposed to be overlapped with thecorresponding lower flow path wall portion 13 of the lower metallicsheet 10 in a planar view, which improves mechanical strength of thevapor chamber 1. Additionally, a width and a height of each upper flowpath wall portion 22 are preferably the same as the width w0 and theheight h0 of each lower flow path wall portion 13 described above. Here,while the bottom surface 21 a of the upper vapor flow path recess 21 canbe also said as a ceiling surface in the vertical dispositionrelationship between the lower metallic sheet 10 and the upper metallicsheet 20 as shown in FIG. 3 etc., this corresponds to a surface on adeeper side of the upper vapor flow path recess 21, so that this isdescribed as the bottom surface 21 a in the present specification.

As shown in FIGS. 3 and 5, an upper peripheral wall 23 is provided at aperipheral portion of the upper metallic sheet 20. The upper peripheralwall 23 is formed to surround the sealed space 3, especially the uppervapor flow path recess 21 to define the sealed space 3. Also, upperalignment holes 24 which execute positioning between the lower metallicsheet 10 and the upper metallic sheet 20 are respectively provided atfour corners of the upper peripheral wall 23 in a planar view. In otherwords, such a configuration is made that each upper alignment hole 24 isdisposed to be overlapped with each of the above-described loweralignment holes 15 at the time of temporary joint which will bedescribed later, which allows positioning between the lower metallicsheet 10 and the upper metallic sheet 20.

The lower metallic sheet 10 and the upper metallic sheet 20 arepermanently joined to each other preferably by the diffused junction.More specifically, as shown in FIG. 3, an upper surface 14 a of thelower peripheral wall 14 of the lower metallic sheet 10 abuts a lowersurface 23 a of the upper peripheral wall 23 of the upper metallic sheet20, so that the lower peripheral wall 14 and the upper peripheral wall23 are joined to each other. Thereby, the sealed space 3 which seals theworking fluid 2 is formed between the lower metallic sheet 10 and theupper metallic sheet 20. Also, the upper surface 13 a of each lower flowpath wall portion 13 of the lower metallic sheet 10 abut the lowersurface 22 a of each upper flow path wall portion 22 of the uppermetallic sheet 20, so that each lower flow path wall portion 13 and thecorresponding upper flow path wall portion 22 are joined to each other.This improves the mechanical strength of the vapor chamber 1.Especially, since the lower flow path wall portions 13 and the upperflow path wall portions 22 according to this embodiment are disposedwith even intervals, the mechanical strength at each portion of thevapor chamber 1 can be equalized. Additionally, the lower metallic sheet10 and the upper metallic sheet 20 may be joined by other methods suchas brazing as long as permanent jointing is performed, not by thediffused junction.

Also, as shown in FIG. 2, the vapor chamber 1 further includes aninjection portion 4 for pouring the working fluid 2 in the sealed space3 at one of a pair of ends in the first direction X. The injectionportion 4 includes a lower injection protruding portion 16 whichprotrudes from an end surface of the lower metallic sheet 10 and anupper injection protruding portion 25 which protrudes from an endsurface of the upper metallic sheet 20. In these components, a lowerinjection flow path recess 17 is formed on an upper surface of the lowerinjection protruding portion 16, and the upper injection flow pathrecess 26 is formed on a lower surface of the upper injection protrudingportion 25. The lower injection flow path recess 17 communicates withthe lower vapor flow path recess 12, and the upper injection flow pathrecess 26 communicates with the upper vapor flow path recess 21. Thelower injection flow path recess 17 and the upper injection flow pathrecess 26 form an injection flow path of the working fluid 2 when thelower metallic sheet 10 and the upper metallic sheet 20 are joined. Theworking fluid 2 passes through the injection flow path and is pouredinto the sealed space 3. Additionally, in this embodiment, while anexample in which the injection portion 4 is provided at one of the pairof ends of the vapor chamber 1 in the first direction X, this is notrestrictive.

Next, the liquid flow path portion 30 of the lower metallic sheet 10will be explained in more detail using FIGS. 3, 4, 6 and 7.

As show in FIGS. 3 and 4, the liquid flow path portion 30 through whichthe working fluid 2 in liquid form passes is provided in the uppersurface 10 a of the lower metallic sheet 10 (more specifically, theupper surface 13 a of each lower flow path wall portion 13). The liquidflow path portion 30 constitutes a part of the above-described sealedspace 3, and communicates with the lower vapor flow path recess 12 andthe upper vapor flow path recess 21 described above.

As shown in FIG. 6, the liquid flow path portion 30 include a first mainflow groove 31, a second main flow groove 32, a third main flow groove33 and a fourth main flow groove 34. The first main flow groove 31 tothe fourth main flow groove 34 respectively linearly extend in the firstdirection X to allow the working fluid 2 in liquid form to pass through,and are arranged in this order in the second direction Y describedabove. In other words, the fourth main flow groove 34 is arranged on anopposite side from the second main flow groove 32 with respect to thethird main flow groove 33. The first main flow groove 31 to the fourthmain flow groove 34 are configured to mainly transport the working fluid2, condensed from the vapor generated at the evaporating portion 11, tothe evaporating portion 11.

A first convex array 41 is provided between the first main flow groove31 and the second main flow groove 32. The first convex array 41includes a plurality of first convex portions 41 a arranged in the firstdirection X. In FIG. 6, each first convex portion 41 a is formed to berectangular such that the first direction X coincides with alongitudinal direction in a planar view. A first communicating groove 51is interposed between the first convex portions 41 a adjacent to eachother. The first communicating groove 51 is formed to extend in thesecond direction Y to allow communication between the first main flowgroove 31 and the second main flow groove 32, and the working fluid 2can reciprocate between the first main flow groove 31 and the secondmain flow groove 32. The first communicating groove 51 is a regionbetween the first convex portions 41 a adjacent to each other, and aregion between the first main flow groove 31 and the second main flowgroove 32.

A second convex array 42 is provided between the second main flow groove32 and the third main flow groove 33. The second convex array 42includes a plurality of second convex portions 42 a arranged in thefirst direction X. In FIG. 6, each second convex portion 42 a is formedto be rectangular such that the first direction X coincides with alongitudinal direction in a planar view. A second communicating groove52 is interposed between the second convex portions 42 a adjacent toeach other. The second communicating groove 52 is formed to extend inthe second direction Y to allow communication between the second mainflow groove 32 and the third main flow groove 33, and the working fluid2 can reciprocate between the second main flow groove 32 and the thirdmain flow groove 33. The second communicating groove 52 is a regionbetween the second convex portions 42 a adjacent to each other, and aregion between the second main flow groove 32 and the third main flowgroove 33.

The second main flow groove 32 includes a first intersection P1communicating with the first communicating groove 51 and a secondintersection P2 communicating with the second communicating groove 52.

In these components, at the first intersection P1, at least a part ofthe first communicating groove 51 faces the second convex portion 42 a.As shown in FIG. 6, at the first intersection P1, the entire firstcommunicating groove 51 (an entire region of the first communicatinggroove 51 in a width direction (the first direction X)) faces the secondconvex portion 42 a. Thereby, over the entire first intersection P1, ina pair of side walls 35, 36 along the first direction X of the secondmain flow groove 32, the side wall 36 on an opposite side from the firstcommunicating groove 51 (a wall of each second convex portion 42 a) isdisposed. In a form shown in FIG. 6, seen from the second direction Y,the first communicating groove 51 is disposed to be overlapped with thecenter of each second convex portion 42 a in the first direction X. Inthis way, at the first intersection P1, the second main flow groove 32and the first communicating groove 51 intersect to form a T shape. Thefirst intersection P1 is a region formed by main flow groove bodyportions 31 a to 34 a adjacent to each other in the first direction X,and a region formed by the communicating grooves 51 to 54 and the convexportions 41 a to 44 a adjacent to each other in the second direction Y.In other words, this is a region in which the main flow grooves 31 to 34and the communicating grooves 51 to 54 intersect (that is, anoverlapping region). Here, the main flow groove body portions 31 a to 34a constitute a part of the first main flow groove 31 to the fourth mainflow groove 34, and are portions provided between the first intersectionP1 and the second intersection P2, and portions positioned between theconvex portions 41 a to 44 a adjacent to each other.

In the same manner, at the second intersection P2, at least a part ofthe second communicating groove 52 faces the first convex portion 41 a.As shown in FIG. 6, at the second intersection P2, the entire secondcommunicating groove 52 (an entire region of the second communicatinggroove 52 in the width direction (the first direction X)) faces eachfirst convex portion 41 a. Thereby, over the entire second intersectionP2, in a pair of side walls 35, 36 along the first direction X of thesecond main flow groove 32, the side wall 35 on an opposite side fromthe second communicating groove 52 (a wall of each first convex portion41 a) is disposed. In the form shown in FIG. 6, seen from the seconddirection Y, the second communicating groove 52 is disposed to beoverlapped with the center of the first convex portion 41 a in the firstdirection X. In this way, at the second intersection P2, the second mainflow groove 32 and the second communicating groove 52 intersect to forma T shape. The second intersection P2 is a region formed by the mainflow groove body portions 31 a to 34 a adjacent to each other in thefirst direction X, and a region formed by the communicating grooves 51to 54 and the convex portions 41 a to 44 a adjacent to each other in thesecond direction Y. In other words, this is a region in which the mainflow grooves 31 to 34 and the communicating grooves 51 to 54 intersect(that is, an overlapping region).

As described above, at the first intersection P1 of the second main flowgroove 32, the first communicating groove 51 faces each second convexportion 42 a, and at the second intersection P2 of the second main flowgroove 32, the second communicating groove 52 faces each first convexportion 41 a. As a result, the first communicating groove 51 and thesecond communicating groove 52 are not disposed in a straight line. Inother words, the first communicating groove 51 communicating with thesecond main flow groove 32 on one side and the second communicatinggroove 52 communicating with the second main flow groove 32 on the otherside are not disposed in the straight line.

In this embodiment, each first convex portion 41 a and each secondconvex portion 42 a have the same shape, and an arrangement pitch of thefirst convex portions 41 a is the same as that of the second convexportions 42 a. Moreover, the first convex portions 41 a and the secondconvex portions 42 a are arranged to be shifted to each other in thefirst direction X by a dimension which is a half of this arrangementpitch.

Also, in this embodiment, the first intersection P1 and the secondintersection P2 of the second main flow groove 32 are adjacent to eachother. In other words, no other intersection (for example, a thirdintersection P3 as shown in FIG. 14 which will be described later) isinterposed between the first intersection P1 and the second intersectionP2. Moreover, the second main flow groove 32 includes a plurality offirst intersections P1 and a plurality of second intersections P2, andeach first intersection P1 and each second intersection P2 arealternately arranged in the first direction X. In other words, the pairof side walls 35, 36 of the second main flow groove 32 is intermittentlyformed, and dividing positions of each of the side walls 35, 36 areshifted to each other in the first direction X.

Incidentally, a third convex array 43 is provided between the third mainflow groove 33 and the fourth main flow groove 34. In the same manner asthe first convex array 41, the third convex array 43 includes aplurality of third convex portions 43 a arranged in the first directionX. A third communicating groove 53 is interposed between the thirdconvex portions 43 a adjacent to each other. The third communicatinggroove 53 is formed to extend in the second direction Y to allowcommunication between the third main flow groove 33 and the fourth mainflow groove 34, and the working fluid 2 can reciprocate between thethird main flow groove 33 and the fourth main flow groove 34. The thirdcommunicating groove 53 is a region formed by the third convex portions43 a adjacent to each other, and a region formed by the third main flowgroove 33 and the fourth main flow groove 34.

The third main flow groove 33 includes the first intersection P1communicating with the second communicating groove 52 and the secondintersection P2 communicating with the third communicating groove 53. Inthese components, at the first intersection P1, at least a part of thesecond communicating groove 52 faces each third convex portion 43 a. Asshown in FIG. 6, at the first intersection P1, the entire secondcommunicating groove 52 (an entire region of the second communicatinggroove 52 in the width direction (the first direction X)) faces eachthird convex portion 43 a. Thereby, over the entire first intersectionP1, in a pair of side walls 35, 36 along the first direction X of thethird main flow groove 33, the side wall 36 on an opposite side from thesecond communicating groove 52 (a wall of each third convex portion 43a) exists. In the form shown in FIG. 6, seen from the second directionY, the second communicating groove 52 is disposed to be overlapped withthe center of each third convex portion 43 a in the first direction X.In this way, at the first intersection P1, the third main flow groove 33and the second communicating groove 52 intersect to form a T shape.

In the same manner, at the second intersection P2, at least a part ofthe third communicating groove 53 faces each second convex portion 42 a.In FIG. 6, at the second intersection P2, the entire of the thirdcommunicating groove 53 (an entire region of the third communicatinggroove 53 in the width direction (the first direction X)) faces eachsecond convex portion 42 a. Thereby, over the entire second intersectionP2, in the pair of side walls 35, 36 along the first direction X of thethird main flow groove 33, the side wall 35 on an opposite side from thethird communicating groove 53 (a wall of each second convex portion 42a) is disposed. In the form shown in FIG. 6, seen from the seconddirection Y, the third communicating groove 53 is disposed to beoverlapped with the center of each second convex portion 42 a in thefirst direction X. In this way, at the second intersection P2, the thirdmain flow groove 33 and the third communicating groove 53 intersect toform a T shape.

In other words, in this embodiment, each first convex portion 41 a, eachsecond convex portions 42 a and each third convex portion 43 a have thesame shape, and the first convex portions 41 a, the second convexportions 42 a and the third convex portions 43 a have the samearrangement pitch. Moreover, each second convex portion 42 a and eachthird convex portion 43 a are arranged to be shifted to each other inthe first direction X by a dimension which is a half of this arrangementpitch. As a result, each first convex portion 41 a and each third convexportion 43 a are arranged at the same position in the first direction X,and seen in the second direction Y, each first convex portion 41 a andeach third convex portion 43 a are overlapped.

In this embodiment, in the same manner as the second main flow groove32, the first intersection P1 and the second intersection P2 of thethird main flow groove 33 are adjacent to each other. Moreover, thethird main flow groove 33 includes the plurality of first intersectionsP1 and the plurality of second intersections P2, and each firstintersection P1 and each second intersection P2 are alternately arrangedin the first direction X. In other words, the pair of side walls 35, 36of the third main flow groove 33 is intermittently formed, and dividingpositions of each of the side walls 35, 36 are shifted to each other inthe first direction X.

Since the first convex portions 41 a, the second convex portions 42 aand the third convex portions 43 a are disposed as described above, inthis embodiment, the first convex portions 41 a, the second convexportions 42 a and the third convex portions 43 a have a staggeredarrangement. As a result, the first communicating groove 51, the secondcommunicating groove 52 and the third communicating groove 53 have thestaggered arrangement.

FIG. 6 shows one set of main flow grooves when the above-described firstmain flow groove 31 to the fourth main flow groove 34 are defined as oneset. This set may be plural, so that multiple main flow grooves 31 to 34may be formed on the upper surface 13 a of each lower flow path wallportion 13 as a whole. Additionally, in the main flow groovesconstituting the liquid flow path portion 30, the first main flow groove31 to the fourth main flow groove 34 do not necessarily constitute oneset, and any number of main flow grooves may be applied, not limited toa multiple of four, as long as at least three main flow grooves areformed.

In this case, on a side of the fourth main flow groove 34 opposite fromthe third main flow groove 33, the above-described first main flowgroove 31 is provided, and a fourth convex array 44 is provided betweenthe fourth main flow groove 34 and the first main flow groove 31. In thesame manner as the second convex array 42, the fourth convex array 44includes a plurality of fourth convex portions 44 a arranged in thefirst direction X. The fourth convex portions 44 a and the second convexportions 42 a are arranged at the same positions in the first directionX, and seen in the second direction Y, each fourth convex portion 44 aand each second convex portion 42 a are overlapped. A fourthcommunicating groove 54 is interposed between the third convex portions43 a adjacent to each other. The fourth communicating groove 54 isformed to extend in the second direction Y to allow communicationbetween the fourth main flow groove 34 and the first main flow groove31, and the working fluid 2 can reciprocate between the fourth main flowgroove 34 and the first main flow groove 31. The fourth communicatinggroove 54 is a region between the fourth convex portions 44 a adjacentto each other, and a region between the fourth main flow groove 34 andthe first main flow groove 31.

The fourth main flow groove 34 includes the first intersection P1 andthe second intersection P2 in the same manner as the second main flowgroove 32. Here, at the first intersection P1, the fourth main flowgroove 34 communicates with the third communicating groove 53, and atthe second intersection P2, the fourth main flow groove 34 communicateswith the fourth communicating groove 54. Also, the first main flowgroove 31 includes the first intersection P1 and the second intersectionP2 in the same manner as the third main flow groove 33. Here, at thefirst intersection P1, the first main flow groove 31 communicates withthe fourth communicating groove 54, and at the second intersection P2,the first main flow groove 31 communicates with the first communicatinggroove 51. Since the first intersection P1 and the second intersectionP2 in the first main flow groove 31 and the fourth main flow groove 34are similar to the first intersection P1 and the second intersection P2in the second main flow groove 32 and the third main flow groove 33, adetailed explanation thereof is omitted here.

Each of the convex portions 41 a to 44 a may be rectangular and have thestaggered arrangement as described above over the entire liquid flowpath portion 30.

Incidentally, a width w1 of the first main flow groove 31 to the fourthmain flow groove 34 (a dimension in the second direction Y) ispreferably larger than a width w2 of each first convex portion 41 a toeach fourth convex portion 44 a (a dimension in the second direction Y.)In such a case, the ratio of the first to fourth main flow grooves 31 to34 to the upper surface 13 a of each lower flow path wall portion 13 canbe made larger. Consequently, a flow path density of the main flowgrooves 31 to 34 on the upper surface 13 a can be increased to improve atransport function of the working fluid 2 in liquid form. For example,the width w1 of the first main flow groove 31 to the fourth main flowgroove 34 may be 30 μm to 200 μm, and the width w2 of each first convexportion 41 a to each fourth convex portion 44 a may be 20 μm to 180 μm.

A depth h1 of the first main flow groove 31 to the fourth main flowgroove 34 is preferably smaller than a depth h0 of the above-describedlower vapor flow path recess 12. In such a case, capillary action of thefirst main flow groove 31 to the fourth main flow groove 34 can beimproved. For example, the depth h1 of the first main flow groove 31 tothe fourth main flow groove 34 is preferably about a half of the depthh0, and may be 5 μm to 180 μm.

Also, a width w3 of the first communicating groove 51 to the fourthcommunicating groove 54 (a dimension in the first direction X) ispreferably smaller than the width w1 of the first main flow groove 31 tothe fourth main flow groove 34. In such a case, during a period that theworking fluid 2 in liquid form is transported toward the evaporatingportion 11 in each of the main flow grooves 31 to 34, the working fluid2 is inhibited from flowing to the communicating grooves 51 to 54, whichimproves the transport function of the working fluid 2. On the otherhand, when dryout occurs at any of the main flow grooves 31 to 34, theworking fluid 2 can be moved from the main flow grooves 31 to 34adjacent thereto via the corresponding communicating grooves 51 to 54,and accordingly, the dryout is immediately eliminated to secure thetransport function of the working fluid 2. In other words, as long aspassage through the main flow grooves 31 to 34 adjacent to each other isallowed, the first communicating groove 51 to the fourth communicatinggroove 54 can exert a function even if they have a smaller width thanthe width w1 of the main flow grooves 31 to 34. The width w3 of suchfirst communicating groove 51 to fourth communicating groove 54 may be20 μm to 180 μm, for example.

The depth h3 of the first communicating groove 51 to the fourthcommunicating groove 54 may be shallower than the depth h1 of the firstmain flow groove 31 to the fourth main flow groove 34 in accordance withthe width w3 thereof. For example, the depth h3 of the firstcommunicating groove 51 to the fourth communicating groove 54 (notshown) may be 40 μm assuming that the depth h1 of the first main flowgroove 31 to the fourth main flow groove 34 is 50 μm.

Here, a method of confirming the width and the depth of the main flowgrooves 31 to 34 and the width and the depth of the communicatinggrooves 51 to 54 from the vapor chamber 1 in a finished form will bedescribed later.

The shape of a cross section (a cross section in the second direction Y)of the first main flow groove 31 to the fourth main flow groove 34 isnot particularly limited, and for example, may be rectangular, curved,semi-circular or V-shaped. The same is applied to the shape of a crosssection (a cross section in the first direction X) of the firstcommunicating groove 51 to the fourth communicating groove 54. In FIG.7, an example in which the cross section of the first main flow grooves31 to the fourth main flow groove 34 is formed to be rectangular isshown.

Incidentally, the above-described liquid flow path portion 30 is formedon the upper surface 13 a of each lower flow path wall portion 13 of thelower metallic sheet 10. On the other hand, in this embodiment, thelower surface 22 a of each upper flow path wall portion 22 of the uppermetallic sheet 20 is formed to be planar. Thereby, each of the main flowgrooves 31 to 34 of the liquid flow path portion 30 is covered by thelower surface 22 a which is planar. In this case, as shown in FIG. 7, bythe pair of side walls 35, 36 extending in the first direction X of themain flow grooves 31 to 34 and the lower surface 22 a of each upper flowpath wall portion 22, two corner portions 37 in a right angle or anacute angle can be formed, which improves capillary action at the twocorner portions 37. In other words, while two corner portions 38 can beformed also by a bottom surface of the main flow grooves 31 to 34 (asurface on the side of the lower surface 10 b of the lower metallicsheet 10) and the pair of side walls 35, 36 of the main flow grooves 31to 34, when the main flow grooves 31 to 34 are formed by etching as willbe described later, the corner portions 38 on the side of the bottomsurface tend to be formed to be rounded. Consequently, capillary actioncan be improved at the corner portions 37 on a side of the lower surface22 a of each upper flow path wall portion 22 by forming the lowersurface 22 a of each upper flow path wall portion 22 to be planar tocover the main flow grooves 31 to 34 and the communicating grooves 51 to54. Additionally, in FIG. 7, for clarity of the figure, the side walls35, 36 and the corner portions 37, 38 are shown only with respect to thefirst main flow groove 31, and the side walls 35, 36 and the cornerportions 37, 38 are omitted with respect to the second main flow groove32 to the fourth main flow groove 34.

Additionally, while a material used for the lower metallic sheet 10 andthe upper metallic sheet 20 is not especially limited as long as thematerial has a good thermal conductivity, for example, the lowermetallic sheet 10 and the upper metallic sheet 20 are preferably formedby copper (an oxygen-free copper) or copper alloy. This improves thermalconductivity of the lower metallic sheet 10 and the upper metallic sheet20. As a result, heat release efficiency of the vapor chamber 1 can beimproved. Alternatively, as long as a desired heat release efficiencycan be obtained, other metallic materials such as aluminum or othermetallic alloy materials such as stainless steel may be used for thesemetallic sheets 10 and 20.

Next, an operation of this embodiment constituted by such configurationwill be explained. Here, firstly, a manufacturing method of the vaporchamber 1 will be explained using FIGS. 8 to 13, but an explanation of ahalf etching step of the upper metallic sheet 20 is simplified.Additionally, in FIGS. 8 to 13, the same cross section as in FIG. 3 isshown.

Firstly as shown in FIG. 8, as a preparation step, a planar metalmaterial sheet M is prepared.

After that, as show in FIG. 9, the metal material sheet M is half-etchedto form the lower vapor flow path recess 12 constituting a part of thesealed space 3. In this case, firstly, a not shown first resist film isformed to have a pattern corresponding to the plurality of lower flowpath wall portions 13 and the lower peripheral wall 14 by aphotolithographic technique on an upper surface Ma of the metal materialsheet M. Thereafter, as a first half etching step, the upper surface Maof the metal material sheet M is half-etched. Thereby, a portion of theupper surface Ma of the metal material sheet M corresponding to a resistopening (not shown) of the first resist film is half-etched, and thelower vapor flow path recess 12, the lower flow path wall portions 13and the lower peripheral wall 14 as shown in FIG. 9 are formed. At thistime, the lower injection flow path recess 17 as shown in FIGS. 2 and 4is simultaneously formed, and the metal material sheet M is etched tohave an outer shape as shown in FIG. 4 from the upper surface Ma and alower surface, thereby a predetermined outer shape can be obtained.After the first half etching step, the first resist film is removed.Additionally, the half etching means etching to form a recess notpenetrating through a material. Consequently, the depth of the recessformed by the half etching is not limited to a half of the thickness ofthe lower metallic sheet 10. As etching liquid, for example, ferricchloride etching liquid such as aqueous ferric chloride, or copperchloride etching liquid such as aqueous copper chloride can be used.

After the lower vapor flow path recess 12 is formed, as shown in FIG.10, the liquid flow path portion 30 is formed on the upper surface 13 aof each lower flow path wall portion 13.

In this case, firstly, a not shown second resist film is formed to havea pattern corresponding to the first convex portions 41 a to the fourthconvex portions 44 a of the liquid flow path portion 30 by thephotolithographic technique on the upper surface 13 a of each lower flowpath wall portion 13. After that, as a second half etching step, theupper surface 13 a of each lower flow path wall portion 13 ishalf-etched. Thereby, a portion of the upper surface 13 a correspondingto a resist opening (not shown) of the second resist film ishalf-etched, and the liquid flow path portion 30 is formed on the uppersurface 13 a of each lower flow path wall portion 13. In other words, onthe upper surface 13 a, each of the convex portions 41 a to 44 a isformed. By these convex portions 41 a to 44 a, the first main flowgroove 31 to the fourth main flow groove 34 and the first communicatinggroove 51 to the fourth communicating groove 54 are defined. After thesecond half etching step, the second resist film is removed.

In this way, the lower metallic sheet 10 formed with the liquid flowpath portion 30 is obtained. Additionally, by forming the liquid flowpath portion 30 as the second half etching step as a different step fromthe first half etching step, the main flow grooves 31 to 34 and thecommunicating grooves 51 to 54 can be easily formed with a depth whichis different from the depth h0 of the lower vapor flow path recess 12.However, the lower vapor flow path recess 12 and the main flow grooves31 to 34 as well as the communicating grooves 51 to 54 may be formedwith the same half etching step. In such a case, the number of halfetching step can be reduced, which can reduce a manufacturing cost ofthe vapor chamber 1.

On the other hand, in the same manner as the lower metallic sheet 10,the upper metallic sheet 20 is half-etched from the lower surface 20 ato form the upper vapor flow path recess 21, the upper flow path wallportions 22 and the upper peripheral wall 23. In this way, theabove-described upper metallic sheet 20 is obtained.

Next, as shown in FIG. 11, as a temporary joint step, the lower metallicsheet 10 having the lower vapor flow path recess 12 and the uppermetallic sheet 20 having the upper vapor flow path recess 21 aretemporarily joined. In such a case, firstly, using the lower alignmentholes 15 of the lower metallic sheet 10 (see FIGS. 2 and 4) and theupper alignment holes 24 of the upper metallic sheet 20 (see FIGS. 2 and5), positioning of the lower metallic sheet 10 and the upper metallicsheet 20 is executed. Thereafter, the lower metallic sheet 10 and theupper metallic sheet 20 are fixed. While a fixing method is notparticularly limited, for example, the lower metallic sheet 10 and theupper metallic sheet 20 are fixed by executing resistance welding to thelower metallic sheet 10 and the upper metallic sheet 20. In this case,as shown in FIG. 11, a resistance spot welding is preferably executedusing an electrode rod 40. Instead of resistance welding, laser weldingmay be executed. Alternatively, ultrasonic junction may be executed tofix the lower metallic sheet 10 and the upper metallic sheet 20 byirradiating ultrasonic waves. Further, an adhesive agent may be used,and the adhesive agent including no or little organic constituent ispreferably used. In this way, the lower metallic sheet 10 and the uppermetallic sheet 20 are fixed with execution of the positioning.

After the temporary joint, as shown in FIG. 12, as a permanent jointstep, the lower metallic sheet 10 and the upper metallic sheet 20 arepermanently joined by the diffused junction. The diffused junction is amethod in which the lower metallic sheet 10 and the upper metallic sheet20 to be joined are closely contacted, and each of the metallic sheets10, 20 is pressurized to be heated in a contact direction in acontrolled atmosphere such as vacuum or inert gas to execute joint usingdiffusion of atoms generated at joint surfaces. While the material ofthe lower metallic sheet 10 and the upper metallic sheet 20 are heatedto a temperature approximate to a melting point in the diffusedjunction, this temperature is lower than the melting point, which avoidsmelting and deformation of each of the metallic sheets 10, 20. Morespecifically, the upper surface 14 a of the lower peripheral wall 14 ofthe lower metallic sheet 10 and the lower surface 23 a of the upperperipheral wall 23 of the upper metallic sheet 20 are subjected to thediffused junction as joint surfaces. Thereby, by the lower peripheralwall 14 and the upper peripheral wall 23, the sealed space 3 is formedbetween the lower metallic sheet 10 and the upper metallic sheet 20.Also, by the lower injection flow path recess 17 (see FIGS. 2 and 4) andthe upper injection flow path recess 26 (see FIGS. 2 and 5), aninjection flow path of the working fluid 2 communicating with the sealedspace 3 is formed. Further, the upper surface 13 a of each lower flowpath wall portion 13 of the lower metallic sheet 10 and the lowersurface 22 a of each upper flow path wall portion 22 of the uppermetallic sheet 20 are subjected to the diffused junction as jointsurfaces, so that mechanical strength of the vapor chamber 1 isimproved. The liquid flow path portion 30 formed on the upper surface 13a of each lower flow path wall portion 13 remains as a flow path of theworking fluid 2 in liquid form.

After the permanent joint, as shown in FIG. 13, as an enclosing step,the working fluid 2 is poured into the sealed space 3 from the injectionportion 4 (see FIG. 2). At this time, firstly, the sealed space 3 isdepressurized by vacuuming, and then the working fluid 2 is poured intothe sealed space 3. At the time of injection, the working fluid 2 passesthrough the injection flow path formed by the lower injection flow pathrecess 17 and the upper injection flow path recess 26. For example,while the enclosing amount of the working fluid 2 depends on theconfiguration of the liquid flow path portion 30 in the vapor chamber 1,it may be 10% to 30% to the entire volume of the sealed space 3.

After the injection of the working fluid 2, the above-describedinjection flow path is sealed. For example, a laser may be irradiated tothe injection portion 4 to seal the injection flow path by partiallymelting the injection portion 4. Thereby, communication between thesealed space 3 and the outside is blocked, and the working fluid 2 isenclosed in the sealed space 3. This prevents leaking of the workingfluid 2 in the sealed space 3 to the outside. Additionally, for sealing,swaging or brazing of the injection portion 4 may be executed.

As described above, the vapor chamber 1 according to this embodiment canbe obtained.

Next, an operation method of the vapor chamber 1, that is, a coolingmethod of the device D will be explained.

The vapor chamber 1 thus obtained is installed in the housing H of themobile terminal etc., and the device D such as the CPU which is anobject of cooling is attached to the lower surface 10 b of the lowermetallic sheet 10. Since the amount of the working fluid 2 poured intothe sealed space 3 is small, the working fluid 2 in liquid form in thesealed space 3 attaches to a wall surface of the sealed space 3, thatis, a wall surface of the lower vapor flow path recess 12, a wallsurface of the upper vapor flow path recess 21 and a wall surface of theliquid flow path portion 30 by surface tension thereof.

When the device D generates heat in this state, the working fluid 2existing at the evaporating portion 11 in the lower vapor flow pathrecess 12 receives the heat from the device D. The received heat isabsorbed as latent heat and the working fluid 2 evaporates(vaporization) to generate the vapor of the working fluid 2. Most of thegenerated vapor diffuses in the lower vapor flow path recess 12 and theupper vapor flow path recess 21 constituting the sealed space 3 (seesolid arrows of FIG. 4). The vapor in the upper vapor flow path recess21 and the lower vapor flow path recess 12 is separated from theevaporating portion 11, and most of the vapor is transported to aperipheral portion of the vapor chamber 1 with a relatively lowtemperature. The diffused vapor is subjected to heat dissipation to thelower metallic sheet 10 and the upper metallic sheet 20 to be cooled.The heat received by the lower metallic sheet 10 and the upper metallicsheet 20 from the vapor is transferred to the outside via the housingmember Ha (see FIG. 3).

Since the vapor is subjected to heat dissipation to the lower metallicsheet 10 and the upper metallic sheet 20, the vapor loses the latentheat absorbed in the evaporating portion 11 and is condensed. Theworking fluid 2 in a liquid form by condensation is attached to the wallsurfaces of the lower vapor flow path recess 12 or the wall surfaces ofthe upper vapor flow path recess 21. Here, since the working fluid 2continues to be evaporated at the evaporating portion 11, the workingfluid 2 at portions other than the evaporating portion 11 in the liquidflow path portion 30 is transported toward the evaporating portion 11(see dashed arrows in FIG. 4). As a result, the working fluid 2 inliquid form attached to the wall surfaces of the lower vapor flow pathrecess 12 and the wall surfaces of the upper vapor flow path recess 21moves toward the liquid flow path portion 30 and is inserted into theliquid flow path portion 30. In other words, the working fluid 2 isinserted into the first main flow groove 31 to the fourth main flowgroove 34 via the first communicating groove 51 to the fourthcommunicating groove 54, so that the first main flow groove 31 to thefourth main flow groove 34 and the first communicating groove 51 to thefourth communicating groove 54 are filled with the working fluid 2 inliquid form. Consequently, due to capillary action of each of the mainflow grooves 31 to 34, the working fluid 2 which is filled obtainsthrust toward the evaporating portion 11, and is smoothly transported tothe evaporating portion 11.

At the liquid flow path portion 30, in the main flow grooves 31 to 34,one communicates with another which is adjacent thereto via thecorresponding communicating grooves 51 to 54.

Thereby, the working fluid 2 in liquid form reciprocates between themain flow grooves 31 to 34 adjacent to each other, which inhibitsoccurrence of dryout in the main flow grooves 31 to 34. Accordingly,capillary action is applied to the working fluid 2 in each of the mainflow grooves 31 to 34, so that the working fluid 2 is smoothlytransported toward the evaporating portion 11.

Also, since each of the main flow grooves 31 to 34 includes theabove-described first intersection P1 and the second intersection P2,loss of capillary action acting on the working fluid 2 in each of themain flow grooves 31 to 34 is prevented. Here, in a case where the firstcommunicating groove 51 and the second communicating groove 52 arearranged in the straight line via the second main flow groove 32 forexample, both of the pair of side walls 35, 36 do not exist at anintersection with the second main flow groove 32. In such a case,capillary action in a direction toward the evaporating portion 11 islost at the intersection, which can reduce the thrust of the workingfluid 2 toward the evaporating portion 11.

On the other hand, in this embodiment, as described above, the firstcommunicating groove 51 communicating with the second main flow groove32 on one side and the second communicating groove 52 communicatingtherewith on the other side are not arranged on the straight line. Insuch a case, as shown FIG. 6, at the first intersection P1, in the pairof side walls 35, 36 along the first direction X of the second main flowgroove 32, the side wall 36 on an opposite side from the firstcommunicating groove 51 is disposed. Thereby, at the first intersectionP1, loss of capillary action in the direction toward the evaporatingportion 11 is prevented. In the same matter, also at the secondintersection P2, since the side wall 35 on an opposite side from thesecond communicating groove 52 is disposed, loss of capillary action inthe direction toward the evaporating portion 11 is prevented. As aresult, reduction of capillary action at each of the intersections P1and P2 can be inhibited, so that the working fluid 2 toward theevaporating portion 11 can be continuously applied capillary action.

Moreover, in this embodiment, the first intersection P1 and the secondintersection P2 of the second main flow groove 32 are alternatelyarranged. In other words, at the first intersection P1 of the secondmain flow groove 32, capillary action can be applied to the workingfluid 2 in the second main flow groove 32 by the side wall 36 on a sideof the second communicating groove 52, while at the second intersectionP2, capillary action can be applied to the working fluid 2 in the secondmain flow groove 32 by the side wall 35 on a side of the firstcommunicating groove 51 on an opposite side from the side wall 36.Consequently, capillary action acting on the working fluid 2 in thesecond main flow groove 32 can be equalized in the width direction (thesecond direction Y).

In this embodiment, each of the first main flow groove 31, the thirdmain flow groove 33 and the fourth main flow groove 34 has the firstintersection P1 and the second intersection P2 in the same manner as thesecond main flow groove 32. This inhibits reduction of capillary actionapplied to the working fluid 2 in the first main flow groove 31 to thefourth main flow groove 34.

The working fluid 2 which has reached the evaporating portion 11receives heat again from the device D to evaporate. In this way, theworking fluid 2 circulates in the vapor chamber 1 while executing achange of phase, that is, repeating evaporation and condensation totransfer heat of the device D for releasing. As a result, the device Dis cooled.

Incidentally, in this embodiment, as described above, in the second mainflow groove 32, the first communicating groove 51 and the secondcommunicating groove 52 are not arranged on the same straight line.Consequently, depending on the attitude of the mobile terminal to whichthe vapor chamber 1 is installed, there is a case where the seconddirection Y is more similar to a direction of a gravitational force thanthe first direction X. With such attitude, if the first communicatinggroove 51 and the second communicating groove 52 are arranged on thesame straight line, it is believed that a part of the working fluid 2 ineach of the main flow grooves 31 to 34 is affected by the gravitationalforce to flow to one side in the second direction Y in each of thecommunicating grooves 51 to 54, so that the working fluid 2 is shiftedto the one side.

However, as in this embodiment, in a case where each of the main flowgrooves 31 to 34 includes the first intersection P1 and the secondintersection P2, the working fluid 2 is inhibited from linearly flowingto one side in the second direction Y. In other words, the working fluid2 can move to the evaporating portion 11 through the main flow grooves31 to 34 while it is directed to the one side in the second direction Y,which inhibits weakening of a flow of the working fluid 2 to theevaporating portion 11. Consequently, the transport function of theworking fluid 2 in liquid form can be improved even if the vapor chamber1 has an attitude in which a gravitational force acts in a direction ofinhibiting the transport function of the working fluid 2.

Incidentally, the sealed space 3 is depressurized as described above.Thereby, the lower metallic sheet 10 and the upper metallic sheet 20receive pressure in a direction of being recessed inwardly from theoutside air. Here, in a case where the first communicating groove 51 andthe second communicating groove 52 are arranged on the straight line viathe second main flow groove 32, an intersection at which the second mainflow groove 32, the first communicating groove 51, and the secondcommunicating groove 52 intersect at a right angle is formed. In such acase, along a groove extending in the second direction Y orthogonal tothe first direction X, the lower metallic sheet 10 and the uppermetallic sheet 20 are recessed inwardly and the corresponding recesstraversing the second main flow groove 32 is formed. In this case, across-sectional area of a flow path of the second main flow groove 32 isreduced, which can increase flow path resistance of the working fluid 2.

On the other hand, in this embodiment, at each of the first intersectionP1 of the second main flow groove 32, the first communicating groove 51faces each second convex portion 42 a. Thereby, even when the lowermetallic sheet 10 and the upper metallic sheet 20 are recessed inwardlyalong the first communicating grooves 51, the corresponding recess isprevented from traversing the second main flow groove 32. This securesthe cross-sectional area of the flow path of the second main flow groove32, and the flow of the working fluid 2 is prevented from being blocked.For example, in a vapor chamber for a mobile terminal requiring a thinbody, due to its thinness, inhibiting concave deformation may bedifficult. However, even when the vapor chamber 1 according to thisembodiment is applied to such vapor chamber for a mobile terminal,according to this embodiment, concave deformation can be effectivelyinhibited. For example, when the thickness (remained thickness) of aportion of the lower metallic sheet 10 formed with the main flow grooves31 to 34 and the communicating grooves 51 to 54 is about 50 μm to 150μm, to inhibit concave deformation, it is contemplated that thestaggered arrangement of the first convex portion 41 a to the fourthconvex portion 44 a may be effective. Also, when the oxygen-free copperis used as a material with a good thermal conductivity, inhibition ofconcave deformation may be difficult due to a low mechanical strength ofthe material. However, the concave deformation can be effectivelyinhibited even when the vapor chamber 1 according to this embodiment ismade by the oxygen-free copper.

In this way, according to this embodiment, as described above, at thefirst intersection P1, in the pair of side walls 35, 36 of the secondmain flow groove 32, the side wall 36 on an opposite side from the firstcommunicating groove 51 can be disposed. Thereby, even when the lowermetallic sheet 10 and the upper metallic sheet 20 are recessed inwardlyalong the first communicating groove 51 due to pressure of the outsideair, the corresponding recess is prevented from traversing the secondmain flow groove 32. In the same manner, at the second intersection P2,in the pair of side walls 35, 36 of the second main flow groove 32, theside wall 35 on an opposite side from the second communicating groove 52can be disposed. Thereby, even when the lower metallic sheet 10 and theupper metallic sheet 20 are recessed inwardly along the firstcommunicating groove 51 due to pressure of the outside air, thecorresponding recess is prevented from traversing the second main flowgroove 32. This secures the cross-sectional area of the flow path of thesecond main flow groove 32, and the flow of the working fluid 2 isprevented from being blocked. As a result, the transport function of theworking fluid 2 in liquid form can be improved, and thermal transportefficiency can be improved.

Also, according to this embodiment, the second main flow groove 32 ofthe liquid flow path portion 30 includes the first intersection P1 atwhich the first communicating groove 51 faces each second convex portion42 a and the second intersection P2 at which the second communicatinggroove 52 faces each first convex portion 41 a. Thereby, at the firstintersection P1, in the pair of side walls 35, 36 of the second mainflow groove 32, the side wall 36 on an opposite side from the firstcommunicating groove 51 can be disposed, and at the second intersectionP2, the side wall 35 on an opposite side from the second communicatinggroove 52 is disposed. Accordingly, capillary action can be continuouslyapplied to the working fluid 2 toward the evaporating portion 11. Also,the working fluid 2 in the second main flow groove 32 can be appliedcapillary action by the side walls 35, 36 disposed at opposite sidesfrom each other at the first intersection P1 and the second intersectionP2. Accordingly, capillary action applied to the working fluid 2 in thesecond main flow groove 32 can be equalized in the second direction Y.This inhibits reduction of the thrust of the working fluid 2 toward theevaporating portion 11 at the intersections P1, P2. As a result, thetransport function of the working fluid 2 in liquid form can beimproved, and thermal transport efficiency can be improved.

Also, according to this embodiment, the first intersection P1 and thesecond intersection P2 of the second main flow groove 32 are adjacent toeach other. Thereby, capillary action acting on the working fluid 2 inthe second main flow groove 32 can be equalized in the width direction.

Also, according to this embodiment, a plurality of first intersectionsP1 and a plurality of second intersections P2 are alternately arranged.Thereby, capillary action applied to the working fluid 2 in the secondmain flow groove 32 can be even more equalized.

Also, according to this embodiment, the liquid flow path portion 30includes the third main flow groove 33, and the third main flow groove33 includes the first intersection P1 at which the second communicatinggroove 52 faces each third convex portion 43 a and the secondintersection P2 at which the third communicating groove 53 faces eachsecond convex portion 42 a. Thereby, in the same manner as theabove-described second main flow groove 32, even when the lower metallicsheet 10 and the upper metallic sheet 20 are recessed inwardly by thepressure of the outside air, the corresponding recess is prevented fromtraversing the third main flow groove 33. Moreover, capillary actionapplied to the working fluid 2 in the third main flow groove 33 can beequalized. This secures the cross-sectional area of the flow path of thethird main flow groove 33. In particular, in this embodiment, the firstmain flow groove 31 and the fourth main flow groove 34 also includesimilar first intersection P1 and second intersection P2. Accordingly,capillary action applied to the working fluid 2 over the entire of theliquid flow path portion 30 is equalized and the cross-sectional area ofthe flow path of each of the main flow grooves 31 to 34 can be secured,which can improve transport efficiency of the working fluid 2 even more.

Also, according to this embodiment, the first intersection P1 and thesecond intersection P2 of the third main flow groove 33 are adjacent toeach other, so that one-sided application of capillary action can beinhibited even more. In particular, since the plurality of firstintersections P1 and the plurality of second intersections P2 arealternately arranged, capillary action applied to the working fluid 2 inthe third main flow groove 33 can be even further equalized.

Also, according to this embodiment, the lower surface 22 a of each upperflow path wall portion 22 of the upper metallic sheet 20 abutting theupper surface 13 a of each lower flow path wall portion 13 is planar tocover the second main flow groove 32. Thereby, at a transverse sectionof each of the main flow grooves 31 to 34 and each of the communicatinggroove 51 to 54, two corner portions 37 in a right angle or an acuteangle (see FIG. 7) can be formed, which improves capillary action actingon the working fluid 2 in each of the main flow grooves 31 to 34 andeach of the communicating grooves 51 to 54 can be improved.

Also, according to this embodiment, the width w1 of the first main flowgroove 31 to the fourth main flow groove 34 is larger than the width w2of the first convex portions 41 a to the fourth convex portions 44 a.This increases the ratio of the first to fourth main flow grooves 31 to34 to the upper surface 13 a of each lower flow path wall portion 13. Asa result, the transport function of the working fluid 2 in liquid formcan be improved.

Further, according to this embodiment, the width w3 of the firstcommunicating groove 51 to the fourth communicating groove 54 is smallerthan the width w1 of the first main flow groove 31 to the fourth mainflow groove 34. Thereby, during the period that the working fluid 2 inliquid form is transported toward the evaporating portion 11 in each ofthe main flow grooves 31 to 34, the working fluid 2 is inhibited fromflowing to the communicating grooves 51 to 54, which improves thetransport function of the working fluid 2. On the other hand, whendryout occurs at any of the main flow grooves 31 to 34, the workingfluid 2 can be moved from the main flow grooves 31 to 34 adjacentthereto via the corresponding communicating grooves 51 to 54, andaccordingly, the dryout is immediately eliminated to secure thetransport function of the working fluid 2.

Additionally, in this embodiment described above, an example in whichthe entire of the first communicating groove 51 faces each second convexportion 42 a at the first intersection P1 of the second main flow groove32 and the entire of the second communicating groove 52 faces each firstconvex portion 41 a at the second intersection P2 has been explained.However, not limited to this, it is sufficient that a part of the firstcommunicating groove 51 (a partial region of the first communicatinggroove 51 in the width direction (the first direction X)) faces eachsecond convex portion 42 a at the first intersection P1. Moreover, it issufficient that a part of the second communicating groove 52 faces thefirst convex portion 41 a at the second intersection P2. In other words,a partial overlapping is acceptable unless the first communicatinggroove 51 and the second communicating groove 52 are overlapped as awhole (unless the first communicating groove 51 and the secondcommunicating groove 52 are arranged on the straight line) seen in thesecond direction Y. Even in this case, the side wall 36 of the secondmain flow groove 32 can be arranged at a part of the first intersectionP1 in the first direction X and the side wall 35 of the second main flowgroove 32 can be arranged at a part of the second intersection P2 in thefirst direction X. Thereby, at the first intersection P1, loss ofcapillary action in the direction toward the evaporating portion 11 isprevented. The same is applied to the first intersection P1 and thesecond intersection P2 in each of the first main flow groove 31, thethird main flow groove 33 and the fourth main flow groove 34.

Also, in this embodiment described above, an example in which each ofthe first main flow groove 31 to the fourth main flow groove 34 includesthe first intersection P1 and the second intersection P2 has beenexplained. However, not limited to this, it is sufficient that the firstintersection P1 and the second intersection P2 may be included in atleast one of the main flow grooves 31 to 34 of the liquid flow pathportion 30.

For example, the liquid flow path portion 30 may have a configuration asshown in FIG. 14. In a form shown in FIG. 14, the second main flowgroove 32 and the fourth main flow groove 34 include the firstintersection P1 and the second intersection P2 in the same manner as theform shown in FIG. 6. However, the first main flow groove 31 and thethird main flow groove 33 do not include the first intersection P1 andthe second intersection P2 as in the form shown in FIG. 6. In otherwords, in the first main flow groove 31, the fourth communicating groove54 and the first communicating groove 51 extending in the seconddirection Y are arranged in the straight line, and the thirdintersection P3 in which the first main flow groove 31, the fourthcommunicating groove 54 and the first communicating groove 51 intersectat a right angle is formed. In the same manner, also in the third mainflow groove 33, the second communicating groove 52 and the thirdcommunicating groove 53 extending in the second direction Y are arrangedin the straight line, and the third intersection P3 in which the thirdmain flow groove 33, the second communicating groove 52 and the thirdcommunicating groove 53 intersect at a right angle is formed. Even insuch form, the second main flow groove and the fourth main flow groove34 include the first intersection P1 and the second intersection P2,which improves the transport function of the working fluid 2 in liquidform in the liquid flow path portion 30.

Also, in this embodiment described above, an example in which theplurality of first intersections P1 and the plurality of secondintersections P2 are alternately arranged in each of the main flowgrooves 31 to 34 has been explained. However, this is not restrictive.For example, the transport function of the working fluid 2 can beimproved as long as one first intersection P1 and one secondintersection P2 are included in each of the main flow grooves 31 to 34.Further, while an example in which the first intersection P1 and thesecond intersection P2 are adjacent to each other in each of the mainflow grooves 31 to 34 has been explained, this is not restrictive. Forexample, in each of the main flow grooves 31 to 34, between the firstintersection P1 and the second intersection P2, an intersection in whichthe communicating grooves 51 to 54 on both sides are arranged in thestraight line and the main flow grooves 31 to 34 and the communicatinggrooves 51 to 54 intersect at a right angle (for example, P3 shown inFIG. 14) may be formed. Even in this case, by the first intersection P1and the second intersection P2, the transport function of the workingfluid 2 in liquid form in the liquid flow path portion 30 can beimproved.

Also, in this embodiment described above, an example in which the firstmain flow groove 31 to the fourth main flow groove and the firstcommunicating groove 51 to the fourth communicating groove 54 intersectat a right angle. However, not limited to this, the first main flowgroove 31 to the fourth main flow groove 34 and the first communicatinggroove 51 to the fourth communicating groove 54 do not necessarilyintersect at a right angle as long as they intersect with each other.

For example, as shown in FIG. 15, a direction of alignment of thecommunicating grooves 51 to 54 may be inclined to the first direction Xand the second direction Y. In this case, an inclining angle θ of thecommunicating grooves 51 to 54 to the first direction X is arbitrary. Inan example shown in FIG. 15, a planar shape of each of the convexportions 41 a to 44 a is a parallelogram. When such shape is applied tothe vapor chamber 1 which is rectangular, four outer edges 1 a, 1 b (seeFIG. 2) constituting the planar outline of the vapor chamber 1 does notintersect at a right angle with the communicating grooves 51 to 54. Insuch a case, deformation by bending along a line extending in the seconddirection Y is prevented, which prevents each of the grooves 31 to 34and 51 to 54 of the liquid flow path portion 30 from being crushed.

Also, the first to fourth main flow grooves 31 to 34 are not necessarilylinearly formed. For example, in FIG. 16, the main flow grooves 31 to 34are meandering, not linear, and extend in the first direction X in alarge sense. More specifically, in the pair of side walls 35, 36 of themain flow groove 31, a curved concave portion and a curved convexportion are alternately arranged to be connected in a smoothlycontinuing manner. In a case where the main flow grooves 31 to 34 areformed as shown in FIG. 16, a contact area between the working fluid 2and the convex portions 41 a to 44 a increases, which improves coolingefficiency of the working fluid 2.

Also, in this embodiment as described above, an example in which theconvex portions 41 a to 44 a are rectangular and arranged in a staggeredmanner over the entire of each liquid flow path portion 30 has beenexplained. However, not limited to this, at least a part of the convexportions 41 a to 44 a may be arranged in a form as shown in FIG. 15 or16 described above. Further, as for the convex portions 41 a to 44 a, atleast two of the staggered arrangement as shown in FIG. 6, thearrangement of FIG. 15 and the arrangement of FIG. 16 may be combined.

Also, in this embodiment described above, an example in which the firstconvex portion 41 a, the second convex portion 42 a, the third convexportion 43 a and the fourth convex portion 44 a have the same shape hasbeen explained. However, not limited to this, the first convex portion41 a to the fourth convex portion 44 a may have different shapes fromeach other.

For example, as shown in FIG. 17, the length in the first direction X ofthe second convex portion 42 a and the fourth convex portion 44 a may belonger than that of the first convex portion 41 a and the third convexportion 43 a. In a form shown in FIG. 17, in the second main flow groove32 and the fourth main flow groove 34, two first intersections P1 areinterposed between two second intersections P2. In other words, thefirst intersection P1 and the second intersection P2 are not alternatelyarranged as shown in FIG. 6. Also, in the first main flow groove 31 andthe third main flow groove 33, two second intersections P2 areinterposed between two first intersections P1, and the firstintersection P1 and the second intersection P2 are not alternatelyarranged. Also in this case, by the first intersection P1 and the secondintersection P2, the transport function of the working fluid 2 in liquidform in the liquid flow path portion 30 can be improved.

Also, in this embodiment described above, an example in which the upperflow path wall portions 22 of the upper metallic sheet 20 extend to beelongated along the first direction X of the vapor chamber 1 has beenexplained. However, not limited to this, the shape of the upper flowpath wall portions 22 is arbitrary. For example, the upper flow pathwall portions 22 may be formed as a cylindrical boss. Also in this case,preferably, each upper flow path wall portion 22 is arranged to beoverlapped with each lower flow path wall portion 13 in a planar view,and the lower surface 22 a of each upper flow path wall portion 22 isallowed to abut the upper surface 13 a of each lower flow path wallportion 13.

Also, in this embodiment described above, an example in which the uppermetallic sheet 20 has the upper vapor flow path recess 21 has beenexplained. However, not limited to this, the upper metallic sheet 20 maybe formed to be planar as a whole, and does not necessarily have theupper vapor flow path recess 21. In such a case, the lower surface 20 aof the upper metallic sheet 20 abuts the upper surface 13 a of the eachlower flow path wall portion 13 as the second abutting surface, whichimproves mechanical strength of the vapor chamber 1.

Also, in this embodiment described above, an example in which the lowermetallic sheet 10 has the lower vapor flow path recess 12 and the liquidflow path portion 30 has been explained. However, not limited to this,if the upper metallic sheet 20 has the upper vapor flow path recess 21,it is acceptable that the lower metallic sheet 10 does not have thelower vapor flow path recess 12 and the liquid flow path portion 30 isprovided in the upper surface 10 a of the lower metallic sheet 10. Insuch a case, as show in FIG. 18, a region formed with the liquid flowpath portion 30 of the upper surface 10 a may be provided in, inaddition to a region facing each upper flow path wall portion 22, aregion excluding each upper flow path wall portion 22 in a region facingthe upper vapor flow path recess 21. In such a case, the number of mainflow grooves 31 to 34 constituting the liquid flow path portion 30 canbe increased, which can improve the transport function of the workingfluid 2 in liquid form. However, the region formed with the liquid flowpath portion 30 is not limited to a form shown in FIG. 18, and isarbitrary as long as the transport function of the working fluid 2 inliquid form can be secured. Also, in the form shown in FIG. 18, thelower surface 22 a (an abutting surface) of each upper flow path wallportion 22 of the upper metallic sheet 20 is formed at a partial regionof the lower surface 20 a of the upper metallic sheet 20 to secure avapor flow path, and the lower surface 22 a of each upper flow path wallportion 22 abuts a part of the region formed with the liquid flow pathportion 30 of the upper surface 10 a of the lower metallic sheet 10.

Also, in this embodiment described above, an example in which the firstmain flow groove 31 to the fourth main flow groove 34 include the firstintersection P1 and the second intersection P2 has been explained.However, not limited to this, even when each of the main flow grooves 31to 34 does not include the intersections P1 and P2, as long as the widthw1 of the first main flow groove 31 to the fourth main flow groove 34 islarger than the width w2 of each first convex portion 41 a to eachfourth convex portion 44 a, the ratio of the first to fourth main flowgrooves 31 to 34 to the upper surface 13 a of each lower flow path wallportion 13 can be made larger. Also in such a case, the transportfunction of the working fluid 2 in liquid form can be improved, whichimproves thermal transport efficiency.

Second Embodiment

Next, a vapor chamber, an electronic device, a metallic sheet for thevapor chamber and a manufacturing method of the vapor chamber accordingto a second embodiment of the present invention will be explained usingFIGS. 19 to 22.

In the second embodiment as shown in FIGS. 19 to 22, a main differenceis that a width of the first to fourth communicating grooves is largerthan a width of the first to fourth main flow grooves, and the otherconfigurations are substantially similar to those in the firstembodiment shown in FIGS. 1 to 18. Additionally, in FIGS. 19 to 22, thesame components as in the first embodiment shown in FIGS. 1 to 18 areapplied the same reference numerals, and a detailed explanation thereofis omitted.

As shown in FIG. 19, in this embodiment, a width w3′ of the firstcommunicating groove 51 to the fourth communicating groove 54 is largerthan the width w1 of the first main flow groove 31 to the fourth mainflow groove 34 (more specifically, the width of a first main flow groovebody portion 31 a to a fourth main flow groove body portion 34 a whichwill be described later). The width w3′ of the communicating grooves 51to 54 may be, for example, 40 μm to 300 μm. In this embodiment, as shownin FIGS. 20 and 21, an example in which the shape of a transversesection of each of the main flow grooves 31 to 34 and the shape of atransverse section of each of the communicating grooves 51 to 54 areformed to be curved will be explained. In such a case, the width ofgrooves 31 to 34 and 51 to 54 is the width of the grooves on the uppersurface 13 a of each lower flow path wall portion 13. In the samemanner, the width of convex portions 41 a to 44 a which will bedescribed later is the width of the convex portions on the upper surface13 a.

Incidentally, also in this embodiment, the lower surface 22 a of eachupper flow path wall portion 22 of the upper metallic sheet 20 is formedto be planar. Thereby, the first main flow groove 31 to the fourth mainflow groove 34 of the liquid flow path portion 30 are covered by theplanar lower surface 22 a. In such a case, as shown in FIG. 20, by thepair of side walls 35, 36 extending in the first direction X of the mainflow grooves 31 to 34 and the lower surface 22 a of each upper flow pathwall portion 22, two corner portions 37 in a right angle or an acuteangle can be formed, which improves capillary action at the two cornerportions 37. In other words, even when the transverse section of each ofthe first to fourth main flow grooves 31 to 34 is formed to be curved,capillary action can be improved at the corner portions 37.

In the same manner, the first to fourth communicating grooves 51 to 54of the liquid flow path portion 30 are covered by the planar lowersurface 22 a. In such a case, as shown in FIG. 21, by the pair of sidewalls 55, 56 extending in the second direction Y of the first to fourthcommunicating grooves 51 to 54 and the lower surface 22 a of each upperflow path wall portion 22, two corner portions 57 in a right angle or anacute angle can be formed, which improves capillary action at the twocorner portions 57. In other words, even when the transverse section ofeach of the first to fourth communicating grooves 51 to 54 is formed tobe curved, capillary action can be improved at the corner portions 57.

Here, the working fluid 2 in liquid form condensed from the vapor passesthrough the first to fourth communicating grooves 51 to 54 to enter thefirst to fourth main flow grooves 31 to 34 which will be describedlater. Consequently, since capillary action of the first to fourthcommunicating grooves 51 to 54 is improved, the working fluid 2condensed in liquid form is allowed to smoothly enter the first tofourth main flow grooves 31 to 34. Due to capillary action of the firstto fourth communicating grooves 51 to 54, the working fluid 2 condensedin liquid form can smoothly enter not only the first main flow groove 31at a closer side to the vapor flow path recesses 12, 21, but also thefirst to fourth main flow grooves 31 to 34 at a farther side from thevapor flow path recesses 12, 21, which improves the transport functionof the working fluid 2 condensed in liquid form. Also, since the widthw3′ of the first to fourth communicating grooves 51 to 54 is larger thanthe width w1 of the first to fourth main flow grooves 31 to 34, the flowpath resistance of the working fluid 2 in the first to fourthcommunicating grooves 51 to 54 can be reduced, and also in this point,the working fluid 2 condensed in liquid form is allowed to smoothlyenter each of the first to fourth main flow grooves 31 to 34. Moreover,the working fluid 2 entering the first to fourth main flow grooves 31 to34 can be smoothly transported to the evaporating portion 11 due tocapillary action of the first to fourth main flow grooves 31 to 34. As aresult, as the entire liquid flow path portion 30, the transportfunction of the working fluid 2 in liquid form can be improved.

Also, both end portions in the first direction X of the first to fourthconvex portions 41 a to 44 a are formed to be rounded in a planar view.In other words, although each of the convex portions 41 a to 44 a isformed to be rectangular in a large sense, a rounded curved portion 45is provided at a corner portion thereof. Thereby, a corner portion ofeach of the convex portions 41 a to 44 a is formed to be smoothlycurved, which reduces the flow path resistance of the working fluid 2 inliquid form. Additionally, such an example is shown that two curvedportions 45 are respectively provided at right and left ends in FIG. 19of the convex portions 41 a to 44 a, and a linear portion 46 is providedbetween the two curved portions 45. Consequently, the width w3′ of thefirst to fourth communicating grooves 51 to 54 is the distance betweenthe linear portions 46 adjacent to each other in the first direction Xof the convex portions 41 a to 44 a. The same is applied to a case whereno curved portion 45 is provided at each of the convex portions 41 a to44 a as shown in FIG. 6. However, the shape of end portions of theconvex portions 41 a to 44 a is not limited to this. For example,instead of providing the linear portion 46 at the right and left endsrespectively, the entire end portion may be curved (for example,semicircular.) In such a case, the width w3′ of each of thecommunicating grooves 51 to 54 is the smallest distance between theconvex portions 41 a to 44 a adjacent to each other in the firstdirection X. Additionally, for clarity of the drawings, in FIG. 19, thecurved portions 45 and the linear portions 46 are shown in the fourthconvex portions 44 a positioned at the bottom as a representative.

As shown in FIGS. 20 and 21, in this embodiment, the width w3′ of thefirst to fourth communicating grooves 51 to 54 is larger than the depthh1 of the first to fourth main flow grooves 31 to 34 (more specifically,the depth of the first to fourth main flow groove body portions 31 a to34 a which will be described later.) Here, when the shape of thetransverse section of each of the main flow grooves 31 to 34 and theshape of the transverse section of each of the communicating grooves 51to 54 are formed to be curved as described above, the depth of thegrooves 31 to 34 and the depth of the communicating grooves 51 to 54 arethe depth at a deepest position in the corresponding groove. The depthh3′ of the first to fourth communicating grooves 51 to 54 may be, forexample, 10 μm to 250 μm.

In this embodiment, as shown in FIG. 22, a depth h1′ of the firstintersection P1 and the second intersection P2 of the first to fourthmain flow grooves 31 to 34 is deeper than the depth h1 of a portion ofthe main flow grooves 31 to 34 excluding the first intersection P1 andthe second intersection P2. In other words, the first to fourth mainflow grooves 31 to 34 further include the first to fourth main flowgroove body portions 31 a to 34 a provided between the firstintersection P1 and the second intersection P2. Each of the first tofourth main flow groove body portions 31 a to 34 a is a portionpositioned between the convex portions 41 a to 44 a adjacent to eachother, and a portion positioned between the first intersection P1 andthe second intersection P2 adjacent to each other. The depth h1′ of thefirst intersection P1 and the second intersection P2 is deeper than thedepth h1 of the first to fourth main flow groove body portions 31 a to34 a. The depth h1′ of the first intersection P1 is a depth at a deepestposition in the first intersection P1, and the depth h1′ of the secondintersection P2 is a depth at a deepest position in the secondintersection P2.

More specifically, as shown in FIGS. 19 and 22, the depth h1′ of thefirst intersection P1 and the second intersection P2 of the first mainflow groove 31 is deeper than the depth h1 of a portion between thefourth convex portion 44 a and the first convex portion 41 a of thefirst main flow groove 31 (the first main flow groove body portion 31a.) In the same manner, the depth h1′ of the first intersection P1 andthe second intersection P2 of the second main flow groove 32 is deeperthan the depth h1 of a portion between the first convex portion 41 a andthe second convex portion 42 a of the second main flow groove 32 (thesecond main flow groove body portion 32 a.) The depth h1′ of the firstintersection P1 and the second intersection P2 of the third main flowgroove 33 is deeper than the depth h1 of a portion between the secondconvex portion 42 a and the third convex portion 43 a of the third mainflow groove 33 (the third main flow groove body portion 33 a.) The depthh1′ of the first intersection P1 and the second intersection P2 of thefourth main flow groove 34 is deeper than the depth h1 of a portionbetween the third convex portion 43 a and the fourth convex portion 44 aof the fourth main flow groove 34 (the fourth main flow groove bodyportion 34 a.)

Also, the depth h1′ of the first intersection P1 and the secondintersection P2 of the first to fourth main flow grooves 31 to 34 may bedeeper than the depth h3′ of the first to fourth communicating grooves51 to 54. The depth h1′ of such first intersection P1 and secondintersection P2 may be, for example, 20 μm to 300 μm.

Also, while the first to fourth convex portions 41 a to 44 a are formedto be rectangular in a large sense as shown in FIG. 19, this shape isdifferent from a planar shape of the first to fourth convex portions 41a to 44 a as shown in FIG. 6. In other words, the first to fourth convexportions 41 a to 44 a include a pair of first to fourth convex endportions 41 b to 44 b provided at both ends in the first direction X andfirst to fourth convex intermediate portions 41 c to 44 c providedbetween the pair of first to fourth convex end portions 41 b to 44 b.Among these, a width w4 of the first to fourth convex intermediateportions 41 c to 44 c is smaller than the width w2 of the first tofourth convex end portions 41 b to 44 b (corresponding to the width w2of the first to fourth convex portions 41 a to 44 a described above.)

More specifically, the width w4 of the first convex intermediate portion41 c is smaller than the width w2 of the first convex end portion 41 b,and walls of the first convex portion 41 a (that is, the side wall 36 ofthe first main flow groove 31 and the side wall 35 of the second mainflow groove 32) are smoothly curved to be recessed toward an innerportion of the first convex portion 41 a. Consequently, the width w4 ofthe first convex intermediate portion 41 c is the smallest distancebetween two walls. In the same manner, the width w4 of the second convexintermediate portion 42 c is smaller than the width w2 of the secondconvex end portion 42 b, and walls of the second convex portion 42 a(that is, the side wall 36 of the second main flow groove 32 and theside wall 35 of the third main flow groove 33) are smoothly curved to berecessed toward an inner portion of the second convex portion 42 a. Thewidth w4 of the third convex intermediate portion 43 c is smaller thanthe width w2 of the third convex end portion 43 b, and walls of thethird convex portion 43 a (that is, the side wall 36 of the third mainflow groove 33 and the side wall 35 of the fourth main flow groove 34)are smoothly curved to be recessed toward an inner portion of the thirdconvex portion 43 a. The width w4 of the fourth convex intermediateportion 44 c is smaller than the width w2 of the fourth convex endportion 44 b, and walls of the fourth convex portion 44 a (that is, theside wall 36 of the fourth main flow groove 34 and the side wall 35 ofthe first main flow groove 31) are smoothly curved to be recessed towardan inner portion of the fourth convex portion 44 a. The width w4 of suchfirst to fourth convex intermediate portions 41 c to 44 c may be, forexample, 15 μm to 175 μm.

As described above, the depth h3′ of the first to fourth communicatinggrooves 51 to 54 is deeper than the depth h1 of the first to fourth mainflow groove body portions 31 a to 34 a of the first to fourth main flowgrooves 31 to 34, and the depth h1′ of the first intersection P1 and thesecond intersection P2 of the first to fourth main flow grooves 31 to 34is deeper than the depth h1 of the first to fourth main flow groove bodyportions 31 a to 34 a. Thereby, a buffer region Q which is deeper thanthe depth h1 of the first to fourth main flow groove body portions 31 ato 34 a is formed at a region from the second intersection P2 througheach of the first to fourth communicating grooves 51 to 54 to the firstintersection P1. The working fluid 2 in liquid form can be stored in thebuffer region Q.

More specifically, for example, the buffer region Q which is deeper thanthe depth h1 of the first main flow groove body portion 31 a and thesecond main flow groove body portion 32 a is formed at a region from thesecond intersection P2 of the first main flow groove 31 through thefirst communicating groove 51 to the first intersection P1 of the secondmain flow groove 32. Typically, each of the main flow grooves 31 to 34and each of the communicating grooves 51 to 54 of the liquid flow pathportion 30 is filled with the working fluid 2 in liquid form.Accordingly, since the depth of the buffer region Q (h1′ and h3′) isdeeper than the depth h1 of the first to fourth main flow groove bodyportions 31 a to 34 a, a large quantity of working fluid 2 can be storedin the buffer region Q. As described above, since each of the main flowgrooves 31 to 34 and each of the communicating grooves 51 to 54 arefilled with the working fluid 2, the working fluid 2 can be stored inthe buffer region Q regardless of the attitude of the vapor chamber 1.

In the same manner, the buffer region Q which is deeper than the depthh1 of the second main flow groove body portion 32 a and the third mainflow groove body portion 33 a is formed at a region from the secondintersection P2 of the second main flow groove 32 through the secondcommunicating groove 52 to the first intersection P1 of the third mainflow groove 33. The buffer region Q which is deeper than the depth h1 ofthe third main flow groove body portion 33 a and the fourth main flowgroove body portion 34 a is formed at a region from the secondintersection P2 of the third main flow groove 33 through the thirdcommunicating groove 53 to the first intersection P1 of the fourth mainflow groove 34. The buffer region Q which is deeper than the depth h1 ofthe fourth main flow groove body portion 34 a and the first main flowgroove body portion 31 a is formed at a region from the secondintersection P2 of the fourth main flow groove 34 through the fourthcommunicating groove 54 to the first intersection P1 of the first mainflow groove 31.

Additionally, while a large number of first intersections P1 and a largenumber of second intersections P2 are formed in each liquid flow pathportion 30 of the vapor chamber 1, as long as the depth h1′ of at leastone of the intersections P1, P2 is deeper than the depth h1 of the mainflow groove body portions 31 a to 34 a (or the depth h3′ of thecommunicating grooves 51 to 54), retaining property of the working fluid2 at the intersections P1, P2 can be improved. Since this retainingproperty improves as the number of intersections P1, P2 having h1′ whichis deeper than the depth h1 of the main flow groove body portions 31 ato 34 a increases, the depth h1′ of all the intersections P1, P2 ispreferably the same depth. However, the retaining property of theworking fluid 2 can be evidently improved even when the depth h1′ of apart of the intersections P1, P2 is not deeper than the depth h1 of themain flow groove body portions 31 a to 34 a due to a production erroretc. The same is applied to the depth h3′ of the communicating grooves51 to 54.

Here, a method of confirming the width and the depth of the main flowgrooves 31 to 34 and the width and the depth of the communicatinggrooves 51 to 54 from the vapor chamber 1 in the finished form will beexplained. Generally, the main flow grooves 31 to 34 and thecommunicating grooves 51 to 54 cannot be seen from the outside of thevapor chamber 1. Consequently, such a method can be listed in which thewidth and the depth of the main flow grooves 31 to 34 and thecommunicating grooves 51 to 54 are confirmed from a cross-sectionalshape obtained by cutting the vapor chamber 1 in the finished form at adesired position.

More specifically, firstly, the vapor chamber 1 is cut by a wire sawinto a 10 mm square piece as a sample. After that, the sample isembedded in resin with vacuum degassing such that resin enters the vaporflow path recesses 12, 21 and the liquid flow path portion 30 (the mainflow grooves 31 to 34 and the communicating grooves 51 to 54.) Next,trimming process is performed by a diamond knife to obtain a desiredcross section. At this time, for example, using a diamond knife of amicrotome (an ultra microtome manufactured by Leica microsystems GmbHetc.), trimming process is executed to a portion away from a measuredobject position by 40 μm. For example, assuming that a pitch of thecommunicating grooves 51 to 54 is 200 μm, by shaving the communicatinggrooves 51 to 54 adjacent to the communicating grooves 51 to 54 as ameasured object by 160 μm, a portion which is 40 μm away from thecommunicating grooves 51 to 54 as the measured object can be specified.Next, a trimming-processed cutting surface is shaved to provide acutting surface for observation. At this time, using a cross sectionsample manufacturing apparatus (for example, a cross section polishermanufactured by JEOL Ltd.), setting a protruding width of 40 μm, thevoltage of 5 kV, and the time of 6 hours, the cutting surface is shavedin ion beam processing. Thereafter, the obtained cutting surface of thesample is observed. At this time, using a scanning electron microscope(for example, a scanning electron microscope manufactured by Carl ZeissCo., Ltd.), setting the voltage of 5 kV, an operation distance of 3 nmand an observation magnification of 200 to 500 times, the cuttingsurface is observed. In this way, the width and the depth of the mainflow grooves 31 to 34 and the communicating grooves 51 to 54 can bemeasured. Additionally, an observation magnification standard at thetime of shooting is polaroid 545. Also, the above-described method isone example, and an apparatus to be used or the measuring condition etc.can be arbitrarily determined in accordance with the shape and theconfiguration etc. of the sample.

Incidentally, as described above, the width w3′ of the first to fourthcommunicating grooves 51 to 54 is larger than the width w1 of the firstto fourth main flow grooves 31 to 34. Thereby, the buffer region Q is aregion which opens wider than the first to fourth main flow groove bodyportions 31 a to 34 a. Consequently, in the second half etching step asshown in FIG. 10, more etching liquid enters the buffer region Q thanthe first to fourth main flow groove body portions 31 a to 34 a. As aresult, erosion by the etching liquid progresses in the buffer region Q,and the depth of the buffer region Q is made deeper. Moreover, in thebuffer region Q, a portion corresponding to the first intersection P1and the second intersection P2 communicates with the first to fourthmain flow groove body portions 31 a to 34 a, so that the etching liquideasily enters this portion than the first to fourth communicatinggrooves 51 to 54. Thereby, the depth h1′ of the first intersection P1and the second intersection P2 can be deeper than the depth h3′ of thefirst to fourth communicating grooves 51 to 54. In this way, the bufferregion Q as shown in FIG. 22 is formed.

Also, because more etching liquid enters the buffer region Q, erosion bythe etching liquid progresses at a portion facing the first intersectionP1 and the second intersection P2 in walls of the first to fourth convexportions 41 a to 44 a (the side walls 35, 36 of the first to fourth mainflow grooves 31 to 34.) Thereby, the walls of the first to fourth convexportions 41 a to 44 a are eroded like boring by the etching liquid toproduce a smoothly curved shape to be recessed toward the inner portionof each of the convex portions 41 a to 44 a.

Additionally, in the second half etching step as shown in FIG. 10, asdescribed above, the second resist film is formed to have a pattern onthe upper surface 13 a of each lower flow path wall portion 13, and theetching liquid enters the resist opening of the second resist film toform the first to fourth main flow grooves 31 to 34 and the first tofourth communicating grooves 51 to 54. Even in a case where this resistopening is formed to be parallel with the first direction X and thesecond direction Y, since the width w3′ of the first to fourthcommunicating grooves 51 to 54 is larger than the width w1 of the firstto fourth main flow grooves 31 to 34, the etching liquid easily entersthe buffer region Q. As a result, the above-described buffer region Qcan be formed.

In the vapor chamber 1 according to this embodiment, the vapor of theworking fluid 2 diffused to the peripheral portion of the vapor chamber1 is cooled to be condensed. The working fluid 2 condensed in liquidform enters the main flow groove 31 through the first to fourthcommunicating grooves 51 to 54. Here, as described above, since thewidth w3′ of the first to fourth communicating grooves 51 to 54 islarger than the width w1 of the first to fourth main flow grooves 31 to34, the flow path resistance of the working fluid 2 in each of thecommunicating grooves 51 to 54 is reduced. Consequently, the workingfluid 2 in liquid form attached to the wall surfaces of each of thevapor flow path recesses 12, 21 passes through each of the communicatinggrooves 51 to 54 to smoothly enter each of the main flow grooves 31 to34. In addition, each of the main flow grooves 31 to 34 and each of thecommunicating grooves 51 to 54 are filled with the working fluid 2 inliquid form.

When the working fluid 2 filled in each of the main flow grooves 31 to34 is transported toward the evaporating portion 11, a part of theworking fluid 2 is directed to the evaporating portion 11 passingthrough the first intersection P1 and the second intersection P2. In thefirst intersection P1 and the second intersection P2, the working fluid2 obtains the thrust toward the evaporating portion 11 mainly fromcapillary action by the corner portions 37 formed by the side walls 35,36 of the first to fourth main flow grooves 31 to 34 and the lowersurface 22 a of each upper flow path wall portion 22.

On the other hand, a part of the working fluid 2 toward the evaporatingportion 11 is drawn into the buffer region Q constituted by the firstintersection P1 or the second intersection P2 to be stored.

Here, when dryout occurs in the first to fourth main flow groove bodyportions 31 a to 34 a, the working fluid 2 stored in the buffer region Qmoves toward an occurrence portion of the dryout. More specifically, forexample, when the dryout occurs at the first main flow groove bodyportion 31 a, the working fluid 2 moves to an occurrence portion of thedryout by capillary action of the first main flow groove body portion 31a from the buffer region Q which is closest to the occurrence portion ofthe dryout. Thereby, the occurrence portion of the dryout is filled withthe working fluid 2 to eliminate the dryout.

Also, in the first to fourth main flow groove body portions 31 a to 34a, when air bubbles are generated in the working fluid 2 in liquid formdue to its vapor, the air bubbles are drawn into the buffer region Q ata downstream side (on a side of the evaporating portion 11) to beretained. Since the depth of the buffer regions Q is deeper than thedepth h1 of the first to fourth main flow groove body portions 31 a to34 a, the air bubbles drawn into the buffer region Q is inhibited frommoving from the buffer region Q to the main flow groove body portions 31a to 34 a. Consequently, the air bubbles generated in the main flowgroove body portions 31 a to 34 a can be captured by the buffer regionQ, which inhibits the flow of the working fluid 2 to the evaporatingportion 11 from being blocked due to the air bubbles.

In this way, according to this embodiment, the width w3′ of the first tofourth communicating grooves 51 to 54 is larger than the width w1 of thefirst to fourth main flow grooves 31 to 34. This reduces the flow pathresistance of the working fluid 2 in each of the communicating grooves51 to 54. As a result, the working fluid 2 in liquid form condensed fromthe vapor is allowed to smoothly enter each of the main flow grooves 31to 34. In other words, the working fluid 2 can smoothly enter not onlythe main flow grooves 31 to 34 at a closer side to the vapor flow pathrecesses 12, 21, but also the main flow grooves 31 to 34 at a fartherside from the vapor flow path recesses 12, 21, which improves thetransport function of the working fluid 2 condensed in liquid form. As aresult, the transport function of the working fluid 2 in liquid form canbe improved, and thermal transport efficiency can be improved.

Also, according to this embodiment, the depth h3′ of the first to fourthcommunicating grooves 51 to 54 is deeper than the depth h1 of the firstto fourth main flow grooves 31 to 34. Thereby, the buffer region Q whichstores the working fluid 2 can be formed at each of the communicatinggrooves 51 to 54. Consequently, when the dryout occurs at the main flowgrooves 31 to 34, the working fluid 2 stored in the buffer region Q canbe moved to the occurrence portion of the dryout. This eliminates thedryout, which recovers the transport function of the working fluid 2 ineach of the main flow grooves 31 to 34. Also, when air bubbles aregenerated in the main flow grooves 31 to 34, the air bubbles can bedrawn into the buffer region Q to be captured. Also from this point, thetransport function of the working fluid 2 in each of the main flowgrooves 31 to 34 can be recovered.

Also, according to this embodiment, the depth h1′ of the firstintersection P1 and the second intersection P2 of the first to fourthmain flow grooves 31 to 34 is deeper than the depth h1 of the first tofourth main flow groove body portions 31 a to 34 a. Thereby, the bufferregion Q can extend to the first intersection P1 and the secondintersection P2. Consequently, the storage volume of the working fluid 2in the buffer region Q can be increased, and the dryout can beeliminated more easily.

Also, according to this embodiment, the depth h1′ of the firstintersection P1 and the second intersection P2 of the first to fourthmain flow grooves 31 to 34 is deeper than the depth h3′ of the first tofourth communicating grooves 51 to 54. Thereby, in the buffer region Q,the depth of the buffer region Q can be made deeper on a side close tothe occurrence portion of the dryout. Consequently, the working fluid 2stored can be smoothly moved to the occurrence portion of the dryout,which eliminates the dryout more easily.

Also, according to this embodiment, the width w4 of the first to fourthconvex intermediate portions 41 c to 44 c of the first to fourth convexportions 41 a to 44 a is smaller than the width w2 of the first tofourth convex end portions 41 b to 44 b. Thereby, a plain area of thefirst intersection P1 and the second intersection P2 can be increased.Consequently, the storage volume of the working fluid 2 in the bufferregion Q can be increased, which eliminates the dryout more easily.

Also, according to this embodiment, the rounded curved portion 45 isprovided at corner portions of each of the convex portions 41 a to 44 a.Thereby, the corner portion of each of the convex portions 41 a to 44 acan be formed to be smoothly curved, which eliminates the flow pathresistance of the working fluid 2 in liquid form.

Third Embodiment

Next, a vapor chamber, a metallic sheet for the vapor chamber and amanufacturing method of the vapor chamber according to a thirdembodiment of the present invention will be explained using FIGS. 23 to25.

In the third embodiment shown in FIGS. 23 to 25, a main difference isthat a main flow groove convex portion protrudes in the first to fourthmain flow grooves, and a communicating groove convex portion protrudesin the first to fourth communicating grooves, and the otherconfigurations are substantially the same as in the second embodiment asshown in FIGS. 19 to 22. Additionally, in FIGS. 23 to 25, the samecomponents as those in the second embodiment as shown in FIGS. 19 to 22are applied the same reference numerals, and a detailed explanationthereof is omitted.

As shown in FIG. 23, in this embodiment, the upper metallic sheet 20includes a plurality of main flow groove convex portions 27 provided inthe lower surface 20 a. Each of the main flow groove convex portions 27protrudes to the corresponding one of the main flow grooves 31 to 34 ofthe lower metallic sheet 10 from the lower surface 20 a. A lower end ofeach main flow groove convex portion 27 is separated from a bottomportion of the main flow grooves 31 to 34, so that the flow path of theworking fluid 2 is secured. Also, each main flow groove convex portion27 is formed to extend in the first direction X along the correspondingone of the main flow grooves 31 to 34.

A cross section of each main flow groove convex portion 27 is formed tobe curved. Also, a lateral edge of each main flow groove convex portion27 contacts or is close to the side walls 35, 36 of the first to fourthmain flow grooves 31 to 34. Thereby, the corner portions 37 formed bythe side walls 35, 36 of the first to fourth main flow grooves 31 to 34and the lower surface 22 a of each upper flow path wall portion 22 areformed to be wedge-shaped (or like an acute angle.) In this way, a crosssection of a flow path defined by the main flow grooves 31 to 34 and themain flow groove convex portions 27 (a cross section of a flow path inthe second direction Y) is formed in a crescent shape as shown in FIG.23.

Also, as shown in FIG. 24 and 25, in this embodiment, the upper metallicsheet 20 includes a plurality of communicating groove convex portions 28provided in the lower surface 20 a. Each communicating groove convexportion 28 protrudes to the corresponding one of the communicatinggroove 51 to 54 of the lower metallic sheet 10 from the lower surface 20a. A lower end of each communicating groove convex portion 28 isseparated from a bottom portion of the communicating grooves 51 to 54,so that the flow path of the working fluid 2 is secured. Also, eachcommunicating groove convex portion 28 is formed to extend in the seconddirection Y along the corresponding one of the communicating grooves 51to 54. At the first intersections P1 and the second intersections P2 ofthe first to fourth main flow grooves 31 to 34, the main flow grooveconvex portions 27 and the communicating groove convex portions 28described above intersect to form a T shape.

A cross section of each communicating groove convex portion 28 is formedto be curved in the same manner as each main flow groove convex portion27. Also, a lateral edge of each communicating groove convex portion 28contacts or is close to the pair of side walls 55, 56 (see FIG. 19)extending in the second direction Y of the first to fourth communicatinggrooves 51 to 54. Thereby, the corner portions 57 formed by the sidewalls 55, 56 of the first to fourth communicating grooves 51 to 54 andthe lower surface 22 a of each upper flow path wall portion 22 is formedto be wedge-shaped (or like an acute angle.) In this way, a crosssection of a flow path defined by the communicating grooves 51 to 54 andthe communicating groove convex portions 28 (a cross section of a flowpath in the first direction X) is formed in a crescent shape as shown inFIG. 24. Also, the cross section of the flow path in the seconddirection Y is formed in an elongated crescent shape as shown in FIG.25, because it is formed such that the cross section of the flow path inthe second direction Y of the first to fourth communicating grooves 51to 54 is interposed between the cross section of the flow path of themain flow grooves 31 to 34 as shown in FIG. 23. Additionally, in FIG.19, for clarity of the drawings, the reference numerals 55, 56 areapplied to the side walls only in the third communicating groove 53. Theside walls 55, 56 correspond to the above-described linear portion 46 ofthe convex portions 41 a to 44 a.

The main flow groove convex portions 27 and the communicating grooveconvex portions 28 are formed, for example, by half etching of the uppermetallic sheet 20 to form the upper flow path wall portions 22 etc., andthen press working of the upper metallic sheet 20 alone. Alternatively,in the permanent joint step as shown in FIG. 12, a welding pressure tobe applied to the lower metallic sheet 10 and the upper metallic sheet20 is increased to form the main flow groove convex portions 27 and thecommunicating groove convex portions 28. In other words, by increasingthe welding pressure, a part of each upper flow path wall portion 22 ofthe upper metallic sheet 20 can be inserted into the first to fourthmain flow grooves 31 to 34 and the first to fourth communicating grooves51 to 54. As a result, the main flow groove convex portions 27 and thecommunicating groove convex portions 28, having a curved cross section,can be formed.

In this way, according to this embodiment, each main flow groove convexportion 27 protrudes to the corresponding one of the main flow grooves31 to 34 of the lower metallic sheet 10 from the lower surface 20 a ofthe upper metallic sheet 20. Thereby, the corner portions 37 formed bythe side walls 35, 36 of the first to fourth main flow grooves 31 to 34and the lower surface 22 a of each upper flow path wall portion 22 canbe formed as a minute space defined by the side walls 35, 36 of thefirst to fourth main flow grooves 31 to 34 and the main flow grooveconvex portions 27. This improves capillary action at the cornerportions 37. As a result, the transport function of the working fluid 2in liquid form in each of the main flow grooves 31 to 34 can beimproved, so that thermal transport efficiency can be improved. Inparticular, even when the first intersection P1 and the secondintersection P2 of each of the main flow grooves 31 to 34 are configuredas the buffer region Q as shown in FIG. 19, a high thrust toward theevaporating portion 11 can be applied to the working fluid 2 at thefirst intersection P1 and the second intersection P2 due to capillaryaction by the main flow groove convex portions 27, which improves thetransport function of the working fluid 2 effectively.

Also, according to this embodiment, a cross section of the main flowgroove convex portions 27 is formed to be curved.

Thereby, the corner portions 37 can have a shape like an end of thecrescent shape. Consequently, capillary action at the corner portions 37can be further improved.

Also, according to this embodiment, each communicating groove convexportion 28 protrudes to the corresponding one of the communicatinggrooves 51 to 54 of the lower metallic sheet 10 from the lower surface20 a of the upper metallic sheet 20. Thereby, the corner portions 57formed by the side walls 55, 56 of the first to fourth communicatinggrooves 51 to 54 and the lower surface 22 a of each upper flow path wallportion 22 can be formed as a minute space defined by the side walls 55,56 of the first to fourth communicating grooves 51 to 54 and thecommunicating groove convex portions 28. This improves capillary actionat the corner portions 57.

Here, the working fluid 2 in liquid form condensed from the vapor passesthrough the first to fourth communicating grooves 51 to 54 to enter thefirst to fourth main flow grooves 31 to 34 as described above.Consequently, since capillary action of the first to fourthcommunicating grooves 51 to 54 is improved, the working fluid 2condensed in liquid form is allowed to smoothly enter the first tofourth main flow grooves 31 to 34. Due to capillary action of the firstto fourth communicating grooves 51 to 54, the working fluid 2 condensedin liquid form can smoothly enter not only the first to fourth main flowgrooves 31 to 34 at a closer side to the vapor flow path recesses 12,21, but also the first to fourth main flow grooves 31 to 34 at a fartherside from the vapor flow path recesses 12, 21, which improves thetransport function of the working fluid 2 condensed in liquid form.Also, since the width w3′ of the first to fourth communicating grooves51 to 54 is larger than the width w1 of the first to fourth main flowgrooves 31 to 34, the flow path resistance of the working fluid 2 in thefirst to fourth communicating grooves 51 to 54 can be reduced, and alsoin this point, the working fluid 2 condensed in liquid form is allowedto smoothly enter each of the first to fourth main flow grooves 31 to34. Moreover, the working fluid 2 entering the first to fourth main flowgrooves 31 to 34 can be smoothly transported to the evaporating portion11 due to capillary action of the first to fourth main flow grooves 31to 34. As a result, as the entire liquid flow path portion 30, thetransport function of the working fluid 2 in liquid form can beimproved. Also, as described above, since capillary action of the firstto fourth communicating grooves 51 to 54 is improved, when the dryoutoccurs, the working fluid 2 can reciprocate among the first to fourthmain flow grooves 31 to 34 due to the capillary action of the first tofourth communicating grooves 51 to 54, so that the dryout can beeliminated.

Also, according to this embodiment, a cross section of the communicatinggroove convex portions 28 is formed to be curved. Thereby, the cornerportions 57 can have a shape like an end of the crescent shape.Consequently, capillary action at the corner portions 57 can be furtherimproved.

Additionally, in this embodiment described above, an example in whichthe cross section of the first to fourth main flow grooves 31 to 34 andthe cross section of the first to fourth communicating grooves 51 to 54are formed to be curved has been explained. However, not limited tothis, the cross section of the first to fourth main flow grooves 31 to34 and the cross section of the first to fourth communicating grooves 51to 54 may be formed to be rectangular as shown in FIG. 7. Also in thiscase, capillary action in the corner portions 37, 57 can be improved, sothat the transport function of the working fluid 2 in liquid form in thefirst to fourth main flow grooves 31 to 34 and the first to fourthcommunicating grooves 51 to 54 can be improved. To make the crosssection rectangular, the main flow grooves 31 to 34 and thecommunicating grooves 51 to 54 are preferably formed by press working orcutting work.

Also, in this embodiment described above, an example in which the widthw3′ of the first to fourth communicating grooves 51 to 54 is larger thanthe width w1 of the first to fourth main flow grooves 31 to 34 has beenexplained. However, not limited to this, as shown in FIG. 6, the widthw3′ of each of the communicating grooves 51 to 54 is not necessarilylarger than the width w1 of the each of the main flow grooves 31 to 34.In other words, an effect of improving the transport function of theworking fluid 2 in liquid form in the main flow grooves 31 to 34 withimprovement of capillary action of the first to fourth main flow grooves31 to 34 by the main flow groove convex portions 27 can be exertedregardless of the magnitude relationship between the width w3′ of thecommunicating grooves 51 to 54 and the width w1 of the main flow grooves31 to 34. In the same manner, an effect of improving the transportfunction of the working fluid 2 condensed in liquid form withimprovement of capillary action of the first to fourth communicatinggrooves 51 to 54 by the communicating groove convex portions 28 can beexerted regardless of the magnitude relationship between the width w3′of the communicating grooves 51 to 54 and the width w1 of the main flowgrooves 31 to 34.

The present invention is not directly limited to the above embodimentsand modifications, and in an implementation phase, can be embodied withmodification of constituent elements without departing the gist of thepresent invention. Also, various inventions can be made by anappropriate combination of a plurality of constituent elements disclosedin the above embodiments and modifications. Several constituent elementsmay be deleted from all the constituent elements shown in theembodiments and modifications. Moreover, in each of the aboveembodiments and modifications, the configuration of the lower metallicsheet 10 may be replaced with the configuration of the upper metallicsheet 20.

1. A vapor chamber in which a working fluid is enclosed, the vaporchamber comprising: a first metallic sheet; a second metallic sheet onthe first metallic sheet; a vapor flow path portion through which avapor of the working fluid passes; and a liquid flow path portionthrough which the working fluid in liquid form passes, wherein theliquid flow path portion is in a surface of the first metallic sheet ona side of the second metallic sheet, the liquid flow path portionincludes a first convex array which includes a plurality of first convexportions arranged in the first direction and separated via a firstcommunicating groove, a main flow grove which extends in a firstdirection and through which the working fluid in liquid form passes, anda second convex array which includes a plurality of second convexportions arranged in the first direction and separated via a secondcommunicating groove, the first convex array, the main flow groove andthe second convex array are arranged in this order in a second directionorthogonal to the first direction, the first communicating groove andthe second communicating groove communicate with the main flow groove,the main flow groove includes a second intersection at which the secondcommunicating groove faces the first convex portion, and a portion ofthe first convex portion facing to the second intersection is recessedtoward an inner portion of the first convex portion in a planar view. 2.The vapor chamber according to claim 1, wherein the main flow grooveincludes a first intersection at which the first communicating groovefaces the second convex portion, and a portion of the second convexportion facing to the first intersection is recessed toward an innerportion of the second convex portion in a planar view.
 3. The vaporchamber according to claim 2, wherein the first intersection and thesecond intersection of the main flow groove are adjacent to each other.4. The vapor chamber according to claim 3, wherein the main flow grooveincludes a plurality of the first intersections and a plurality of thesecond intersections, and the first intersections and the secondintersections of the main flow groove are alternately arranged.
 5. Anelectronic device comprising: a housing; a device housed in the housing;and the vapor chamber according to claim 1, wherein the vapor chamber isthermally contacted to the device.
 6. A metallic sheet for a vaporchamber used for the vapor chamber in which a working fluid is enclosed,the vapor chamber including a vapor flow path portion through which avapor of the working fluid passes; and a liquid flow path portionthrough which the working fluid in liquid form passes, the metallicsheet for the vapor chamber comprising: a first face; a second surfaceon an opposite side from the first surface, wherein the liquid flow pathportion is on the first surface, the liquid flow path portion includes afirst convex array which includes a plurality of first convex portionsarranged in the first direction and separated via a first communicatinggroove, a main flow grove which extends in a first direction and throughwhich the working fluid in liquid form passes, and a second convex arraywhich includes a plurality of second convex portions arranged in thefirst direction and separated via a second communicating groove, thefirst convex array, the main flow groove and the second convex array arearranged in this order in a second direction orthogonal to the firstdirection, the first communicating groove and the second communicatinggroove communicate with the main flow groove, the main flow grooveincludes a second intersection at which the second communicating groovefaces the first convex portion, and a portion of the first convexportion facing to the second intersection is recessed toward an innerportion of the first convex portion in a planar view.
 7. The metallicsheet for the vapor chamber according to claim 6, wherein the main flowgroove includes a first intersection at which the first communicatinggroove faces the second convex portion, and a portion of the secondconvex portion facing to the first intersection is recessed toward aninner portion of the second convex portion in a planar view.
 8. Themetallic sheet for the vapor chamber according to claim 7, wherein thefirst intersection and the second intersection of the main flow grooveare adjacent to each other.
 9. The metallic sheet for the vapor chamberaccording to claim 8, wherein the main flow groove includes a pluralityof the first intersections and a plurality of the second intersections,and the first intersections and the second intersections of the mainflow groove are alternately arranged.
 10. A manufacturing method of avapor chamber including a first metallic sheet, a second metallic sheeton the first metallic sheet, a vapor flow path portion through which avapor of the working fluid passes; and a liquid flow path portionthrough which the working fluid in liquid form passes, the manufacturingmethod for the vapor chamber comprises: half-etching in which a surfaceof the first metallic sheet on a side of the second metallic sheet ishalf-etched to form the liquid flow path portion; joining the firstmetallic sheet and the second metallic sheet; and enclosing the workingfluid, wherein the liquid flow path portion is in a surface of the firstmetallic sheet on a side of the second metallic sheet, the liquid flowpath portion includes a first convex array which includes a plurality offirst convex portions arranged in the first direction and separated viaa first communicating groove, a main flow grove which extends in a firstdirection and through which the working fluid in liquid form passes, anda second convex array which includes a plurality of second convexportions arranged in the first direction and separated via a secondcommunicating groove, the first convex array, the main flow groove andthe second convex array are arranged in this order in a second directionorthogonal to the first direction, the first communicating groove andthe second communicating groove communicate with the main flow groove,the main flow groove includes a second intersection at which the secondcommunicating groove faces the first convex portion, and a portion ofthe first convex portion facing to the second intersection is recessedtoward an inner portion of the first convex portion in a planar view.